Dawn and dusk simulation as a therapeutic intervention

Selecting, implementing and evaluating control and placebo conditions in light therapy and light-based interventions

Introduction: Light profoundly influences human physiology, behaviour and cognition by affecting various functions through light-sensitive cells in the retina. Light therapy has proven effective in treating seasonal depression and other disorders. However, designing appropriate control conditions for light-based interventions remains a challenge.Materials and methods: This article presents a novel framework for selecting, implementing and evaluating control conditions in light studies, offering theoretical foundations and practical guidance. It reviews the fundamentals of photoreception and discusses control strategies such as dim light, darkness, different wavelengths, spectral composition and metameric conditions. Special cases like dynamic lighting, simulated dawn and dusk, complex interventions and studies involving blind or visually impaired patients are also considered.Results: The practical guide outlines steps for selection, implementation, evaluation and reporting, emphasizing the importance of α-opic calculations and physiological validation.Conclusion: In conclusion, constructing effective control conditions is crucial for demonstrating the efficacy of light interventions in various research scenarios.

Assessing the Feasibility and Efficacy of Pre-Sleep Dim Light Therapy for Adults with Insomnia: A Pilot Study

Background: Insomnia is increasingly recognized for its marked impact on public health and is often associated with various adverse health outcomes, including cardiovascular diseases and mental health disorders. The aim of this study was to investigate the efficacy of pre-sleep dim light therapy (LT) as a non-pharmacological intervention for insomnia in adults, assessing its influence on sleep parameters and circadian rhythms. Methods: A randomized, open-label, two-arm clinical trial was conducted over two weeks with 40 participants aged 20-60 years, all of whom had sleep disorders (CRIS, KCT0008501). They were allocated into control and LT groups. The LT group received exposure to warm-colored light, minimizing the blue spectrum, before bedtime. The study combined subjective evaluation via validated, sleep-related questionnaires, objective sleep assessments via actigraphy, and molecular analyses of circadian clock gene expression in peripheral blood mononuclear cells. Baseline characteristics between the two groups were compared using an independent t-test for continuous variables and the chi-squared test for categorical variables. Within-group differences were assessed using the paired t-test. Changes between groups were analyzed using linear regression, adjusting for each baseline value and body mass index. The patterns of changes in sleep parameters were calculated using a linear mixed model. Results: The LT group exhibited significant improvements in sleep quality (difference in difference [95% CI]; -2.00 [-3.58, -0.43], and sleep efficiency (LT: 84.98 vs. control: 82.11, p = 0.032), and an advanced Dim Light Melatonin Onset compared to the control group (approximately 30 min). Molecular analysis indicated a significant reduction in CRY1 gene expression after LT, suggesting an influence on circadian signals for sleep regulation. Conclusions: This study provides evidence for the efficacy of LT in improving sleep quality and circadian rhythm alignment in adults with insomnia. Despite limitations, such as a small sample size and short study duration, the results underscore the potential of LT as a viable non-pharmacological approach for insomnia. Future research should expand on these results with larger and more diverse cohorts followed over a longer period to validate and further elucidate the value of LT in sleep medicine. Trial registration: The trial was registered with the Clinical Research Information Service (KCT0008501).

The Efficacy of a Multimodal Bedroom-Based 'Smart' Alarm System on Mitigating the Effects of Sleep Inertia

Previous work has demonstrated the modest impact of environmental interventions that manipulate lighting, sound, or temperature on sleep inertia symptoms. The current study sought to expand on previous work and measure the impact of a multimodal intervention that collectively manipulated light, sound, and ambient temperature on sleep inertia. Participants slept in the lab for four nights and were awoken each morning by either a traditional alarm clock or the multimodal intervention. Feelings of sleep inertia were measured each morning through Psychomotor Vigilance Test (PVT) assessments and ratings of sleepiness and mood at five time-points. While there was little overall impact of the intervention, the participant's chronotype and the length of the lighting exposure on intervention mornings both influenced sleep inertia symptoms. Moderate evening types who received a shorter lighting exposure (≤15 min) demonstrated more lapses relative to the control condition, whereas intermediate types exhibited a better response speed and fewer lapses. Conversely, moderate evening types who experienced a longer light exposure (>15 min) during the intervention exhibited fewer false alarms over time. The results suggest that the length of the environmental intervention may play a role in mitigating feelings of sleep inertia, particularly for groups who might exhibit stronger feelings of sleep inertia, including evening types.

The importance of residential dusk and dawn light exposure for sleep quality, health, and well-being

Light exposure during twilight plays a critical role in the entrainment of the human circadian system. People are most often at home during dusk and dawn, and light exposure at home - either natural or from electric light - may therefore contribute substantially to sleep and well-being. However, very little research has focused on the effects of home lighting on sleep and well-being, and even less research has investigated the effects of light exposure during twilight. Therefore, a literature study was performed to collect studies on light exposure at home during dusk and dawn. Studies looking at light exposure during dusk and dawn have focused on either electric light intervention (i.e., dusk and dawn simulation) at home or in the laboratory or daylight exposure in the bedroom (i.e., the presence and type of curtains in the bedroom). Most research has focused on dawn simulation during the darker months of the year, often using sunrise alarms. In general, study results pointed to the importance of twilight light exposure at home for sleep and well-being. These results may depend on the characteristics of the user, such as age or chronotype.

Light Therapy to Improve Sleep Quality in Older Adults Living in Residential Long-Term Care: A Systematic Review

OBJECTIVES

Because light can regulate sleep rhythms, numerous studies have investigated whether light therapy can improve sleep disorders in older people, but its efficacy remains controversial. Therefore, this systematic review aimed to examine and summarize current evidence about the efficacy of light therapy to improve sleep for older people in residential long-term care.

DESIGN

Systematic review.

SETTING AND PARTICIPANTS

Older people living in long-term care settings.

METHODS

Systematic searches were conducted in the databases PubMed, Web of Science, Cochrane, EMBASE, CINAHL, China National Knowledge Infrastructure, China Science and Technology Journal Database, WanFang, Chinese Biomedical Literature Database, and in reference lists within relevant articles. Studies were eligible for inclusion if they evaluated light therapy for older people with sleep disorders in long-term care settings.

RESULTS

This systematic review includes 21 articles, summarizing light therapy with different durations and intensities. The light intervention was typically administered between 7:00 and 12:00 am for 30-120 minutes. The interventions lasted from 1 week to several months, and the intensity of the light intervention usually ranged from 2500 to 10,000 lux. Short-term exposure (30-60 minutes) with high light levels (≥10,000 lux), relatively long-term exposure (1-2 hours) with moderate light levels (2500-10,000 lux), or long-term exposure (1-4 hours or full day) with low light levels (≤2500 lux) were associated with improved sleep indicators for older people in long-term care settings.

CONCLUSIONS AND IMPLICATIONS

The efficacy of light therapy in long-term care settings may be affected by the duration of exposure, time and length of intervention, intensity of light, and equipment used to administer the therapy. Further research must be conducted to optimize light therapy parameters. Large, high-quality randomized controlled trials are needed to deepen our understanding of the effects of light therapy on sleep in older people living in long-term care settings.

Effects of dynamic bedroom lighting on measures of sleep and circadian rest-activity rhythm in inpatients with major depressive disorder

Bright light therapy is an effective treatment option for seasonal and non-seasonal affective disorders. However up to now, no study has investigated effects of dynamic bedroom lighting in hospitalized patients with major depression. A bedroom lighting system, which automatically delivered artificial dawn and dusk and blue-depleted nighttime lighting (DD-N lighting) was installed in a psychiatric ward. Patients with moderate to severe depression were randomly assigned to stay in bedrooms with the new lighting or standard lighting system. Patients wore wrist actimeters during the first two treatment weeks. Additionally, hospitalization duration and daily psychotropic medication were retrieved from patients' medical charts. Data from thirty patients, recorded over a period of two weeks, were analyzed. Patients under DD-N lighting generally woke up earlier (+ 20 min), slept longer (week 1: + 11 min; week 2: + 27 min) and showed higher sleep efficiency (+ 2.4%) and shorter periods of nighttime awakenings (- 15 min). In the second treatment week, patients started sleep and the most active 10-h period earlier (- 33 min and - 64 min, respectively). This pilot study gives first evidence that depressed patients' sleep and circadian rest/activity system may benefit from bedroom lighting when starting inpatient treatment.

Changing color and intensity of LED lighting across the day impacts on circadian melatonin rhythms and sleep in healthy men

We examined whether dynamically changing light across a scheduled 16-h waking day influences sleepiness, cognitive performance, visual comfort, melatonin secretion, and sleep under controlled laboratory conditions in healthy men. Fourteen participants underwent a 49-h laboratory protocol in a repeated-measures study design. They spent the first 5 hours in the evening under standard lighting, followed by an 8-h nocturnal sleep episode at habitual bedtimes. Thereafter, volunteers either woke up to static light or to a dynamic light that changed spectrum and intensity across the scheduled 16-h waking day. Following an 8-h nocturnal sleep episode, the volunteers spent another 11 hours either under static or dynamic light. Static light attenuated the evening rise in melatonin levels more compared to dynamic light as indexed by a significant reduction in the melatonin AUC prior to bedtime during static light only. Participants felt less vigilant in the evening during dynamic light. After dynamic light, sleep latency was significantly shorter in both the baseline and treatment night while sleep structure, sleep quality, cognitive performance, and visual comfort did not significantly differ. The study shows that dynamic changes in spectrum and intensity of light promote melatonin secretion and sleep initiation in healthy men.

Effects of a dawn-dusk simulation on circadian rest-activity cycles, sleep, mood and well-being in dementia patients

Light is the most powerful "zeitgeber" signal to synchronize circadian sleep-wake cycles. In dementia, these rhythms are often fragmented - probably due to loss of neuronal function of the suprachiasmatic nuclei (the biological "master clock" in the brain) and/or weakness of external zeitgebers. We investigated the effects of a prototype dawn-dusk simulator (DDS) on circadian rest-activity cycles, sleep, mood and well-being in a balanced crossover design during fall and winter in 20 institutionalized patients with dementia (86 ± 6 y, 17 f). All participants had one baseline week followed by exposure to individually timed DDS over their beds for 7-8 weeks. They spent 8 weeks without DDS as a control. Mood, self-reliant daily activity, social behavior, agitation, and quality of life were assessed by standardized questionnaires and visual analogue scales, regularly rated by trained caregivers. Circadian and sleep characteristics of their rest-activity cycles were analyzed by actimetry over 17 weeks. DDS exposure led to significantly better mood in the morning hours after waking. The effects were most pronounced in the second 4 weeks with DDS, indicating that positive effects emerged gradually. Differences in circadian rest-activity cycles and sleep were mainly age-dependent. We found statistically significant correlations between measures of higher quality of life and better mood, greater alertness and circadian rhythm stability. We conclude that continuous, long-term application of dawn-dusk simulation at the sleep-wake transitions appears to increase external zeitgeber strength in institutionalized patients with dementia. The DDS may provide an effective, non-invasive tool to improve mood and ameliorate patients' quality of life.

Precision Light for the Treatment of Psychiatric Disorders

Circadian timekeeping can be reset by brief flashes of light using stimulation protocols thousands of times shorter than those previously assumed to be necessary for traditional phototherapy. These observations point to a future where flexible architectures of nanosecond-, microsecond-, and millisecond-scale light pulses are compiled to reprogram the brain's internal clock when it has been altered by psychiatric illness or advanced age. In the current review, we present a chronology of seminal experiments that established the synchronizing influence of light on the human circadian system and the efficacy of prolonged bright-light exposure for reducing symptoms associated with seasonal affective disorder. We conclude with a discussion of the different ways that precision flashes could be parlayed during sleep to effect neuroadaptive changes in brain function. This article is a contribution to a special issue on Circadian Rhythms in Regulation of Brain Processes and Role in Psychiatric Disorders curated by editors Shimon Amir, Karen Gamble, Oliver Stork, and Harry Pantazopoulos.

Role of Chronobiology as a Transdisciplinary Field of Research: Its Applications in Treating Mood Disorders

Chronobiology is a field that studies the effects of time on biological systems. Periodicity is of particular interest. The master biological clock in the suprachiasmatic nucleus controls daily rhythms of core body temperature, rest-activity cycle, physiological and behavioral functions, psychomotor functions and mood in humans. The clock genes are involved in the generation of the circadian rhythms and the biological clock is synchronized to solar day by direct photic inputs. Various circadian rhythm abnormalities have been demonstrated in mood disorders such as unipolar depression, bipolar depression and seasonal affective disorder. Hypotheses involving circadian rhythm abnormalities related to the etiology of mood disorders have been raised. The resulting circadian rhythm changes can be measured and evaluated that these techniques can be used to identify subtypes of mood disorders associated with circadian rhythm changes. The data obtained from chronobiological studies reveal methods that manipulate circadian rhythms. The effects of light and melatonin on circadian rhythms are determined by these studies. Chronobiological research has been applied to the psychiatric clinic and light therapy has been used as a chronotherapeutic in the treatment of mood disorders. On the other hand, chronotherapeutic approaches with effects on circadian rhythms such as sleep deprivation therapy have been used in the treatment of mood disorders too. As a good example of translational psychiatry, chronobiological studies have been projected in the psychiatry clinic. It may be possible, the data obtained from the basic sciences are used in the diagnosis of mood disorders and in the treatment of psychiatric disorders as chronotherapeutic techniques. Developments in the field of chronobiology and data obtained from chronotherapeutics may enable the development of evidence-based diagnosis and treatment in psychiatry.

Seasonal affective disorder, winter type: current insights and treatment options

Seasonal affective disorder (SAD), winter type, is a seasonal pattern of recurrent major depressive episodes most commonly occurring in autumn or winter and remitting in spring/summer. The syndrome has been well-known for more than three decades, with light treatment being the treatment of first choice. In this paper, an overview is presented of the present insights in SAD. Description of the syndrome, etiology, and treatment options are mentioned. Apart from light treatment, medication and psychotherapy are other treatment options. The predictable, repetitive nature of the syndrome makes it possible to discuss preventive treatment options. Furthermore, critical views on the concept of SAD as a distinct diagnosis are discussed.

Humoral Phototransduction: Blood Is a Messenger

Drawing upon the premise that there is a parsimony to nature, the author proposes that heme moieties and bile pigments in animals mediate some non-visual influences of light upon neuroactive gases and biological rhythms. Primary abnormalities in synthesis and regulation of blood and bile may, therefore, cause some neuropsychiatric illnesses. Light may play a critical role in neurotransmission. NEUROSCIENTIST 2:207-210, 1996

Chronobiological Therapy for Mood Disorders

Chronobiological therapies for mood disorders include manipulations of the sleep-wake cycle such as sleep deprivation and sleep phase advance and the controlled exposure to light and darkness. Their antidepressant efficacy can overcome drug resistance and targets the core depressive symptoms including suicide, thus making them treatment options to be tried either alone or as adjunctive treatments combined with common psychopharmacological interventions. The specific pattern of mood change observed with chronobiological therapies is characterized by rapid and sustained effects, when used among themselves or combined with drugs. Effects sizes are the same reported for the most effective psychiatric treatments, but side effects are usually marginal or absent. New treatment protocols are developed to adapt them in different clinical settings. This review deals with the general principles of clinical chronobiology and the latest findings in this rapidly developing field.

Dawn simulation vs. bright light in seasonal affective disorder: Treatment effects and subjective preference

BACKGROUND

Studies comparing the efficacy of dawn simulation to conventional bright light for the treatment of seasonal affective disorder (in parallel groups) have yielded conflicting results. This crossover study investigated treatment outcomes and long-term treatment preference.

METHODS

Forty winter depressives were treated for a week with bright light (4.300lx for 30-45min shortly after awakening) or dawn simulation (gradually increasing light during the last 30min of sleep achieving 100lx before alarm beep, with the dawn simulator placed closer to the open eyes for a further 15min: 250lx). The depression level was self-rated using SIGH-SAD-SR.

RESULTS

Depression scores reduced similarly following bright light and dawn simulation: for 43.8% and 42.2% (medians), respectively; efficacy ratio was 23:17. The preference was also similar (21:19). Among those who preferred bright light, the most common reason was that they perceived the bright light to be more effective (19/21; it was more effective, p=0.0096; this subgroup tended to have more severe depression) and ease of use (6/21). Among those who preferred the dawn simulator, the reasons were a more "natural" action (9/19), device compactness and/or time-saving (10/19) and in 4 cases where bright light caused eyestrain.

LIMITATIONS

Not overhead naturalistic light for dawn simulation, self-rating of depression.

CONCLUSIONS

Dawn simulation is similarly effective to bright light in the treatment of winter depression. Patients with more severe depression tended to report greater improvement with bright light; in such cases, this would outweigh the non-clinical advantages of dawn simulation.

Protecting the melatonin rhythm through circadian healthy light exposure

Currently, in developed countries, nights are excessively illuminated (light at night), whereas daytime is mainly spent indoors, and thus people are exposed to much lower light intensities than under natural conditions. In spite of the positive impact of artificial light, we pay a price for the easy access to light during the night: disorganization of our circadian system or chronodisruption (CD), including perturbations in melatonin rhythm. Epidemiological studies show that CD is associated with an increased incidence of diabetes, obesity, heart disease, cognitive and affective impairment, premature aging and some types of cancer. Knowledge of retinal photoreceptors and the discovery of melanopsin in some ganglion cells demonstrate that light intensity, timing and spectrum must be considered to keep the biological clock properly entrained. Importantly, not all wavelengths of light are equally chronodisrupting. Blue light, which is particularly beneficial during the daytime, seems to be more disruptive at night, and induces the strongest melatonin inhibition. Nocturnal blue light exposure is currently increasing, due to the proliferation of energy-efficient lighting (LEDs) and electronic devices. Thus, the development of lighting systems that preserve the melatonin rhythm could reduce the health risks induced by chronodisruption. This review addresses the state of the art regarding the crosstalk between light and the circadian system.

Effects of dawn simulation on markers of sleep inertia and post-waking performance in humans

PURPOSE

To examine the effects of a simulated dawn during the last 30 min of sleep on the subsequent dissipation of sleep inertia and changes in simulated work and physical performance.

METHODS

Eight participants, who reported difficulty with morning waking, were administered in a random order to a control (C) and a dawn simulation (DS) trial (starting 30 min prior to waking). Subjective ratings of sleep quality and alertness were obtained alongside measures of cognitive performance (addition and reaction time tasks measured at 5, 30 and 75 min after waking at habitual workday times). Physical performance was also measured 35 min after waking using a self-paced cycling protocol.

RESULTS

After waking in DS, perceived sleep quality was 1.16 ± 0.89 (p = 0.01) points higher compared with C. Ratings of alertness were significantly higher in DS than C throughout the testing period (p = 0.04). Cognitive performance improved in both trials as time awake increased (p < 0.0005). On average, participants completed a greater number of additions in DS compared with C (69.5 ± 15.3 vs 66.9 ± 16.7, p = 0.03). Reaction times were also faster in DS compared with C (0.81 ± 0.07 s vs 0.86 ± 0.06 s, p < 0.0005). The self-paced time-trial was completed 21.4 s (4.7 %) quicker in DS (p = 0.07).

CONCLUSION

These data provide the first evidence that light exposure during the last 30 min of habitual sleep can increase subjective alertness and improve both cognitive and physical performance after waking.

Antidepressant chronotherapeutics for bipolar depression

Chronotherapeutics refers to treatments based on the principles of circadian rhythm organization and sleep physiology, which control the exposure to environmental stimuli that act on biological rhythms, in order to achieve therapeutic effects in the treatment of psychiatric conditions. It includes manipulations of the sleep-wake cycle such as sleep deprivation and sleep phase advance, and controlled exposure to light and dark. The antidepressant effects of chronotherapeutics are evident in difficult-to-treat conditions such as bipolar depression, which has been associated with extremely low success rates of antidepressant drugs in naturalistic settings and with stable antidepressant response to chronotherapeutics in more than half of the patients. Recent advances in the study of the effects of chronotherapeutics on neurotransmitter systems, and on the biological clock machinery, allow us to pinpoint its mechanism of action and to transform it from a neglected or “orphan” treatment to a powerful clinical instrument in everyday psychiatric practice.

Treatment of seasonal affective disorders

Seasonal affective disorder (SAD) is a subform of major depressive disorder, recurrent, or bipolar disorder with a regular onset of depressive episodes at a certain time of year, usually the winter. The treatment of SAD is similar to that of other forms of affective disorder, except that bright light therapy is recommended as the first-line option. Light therapy conventionally involves exposure to visible light of at least 2500 lux intensity at eye level. The effects of light therapy are thought to be mediated exclusively by the eyes, not the skin, although this assumption has not yet been verified. Morning light therapy has proven to be superior to treatment regimens in the evening. Response rates to light therapy are about 80% in selected patient populations, with atypical depressive symptoms being the best predictor of a favorable treatment outcome. Data from randomized, controlled trials suggest that antidepressants are effective in the treatment of SAD. Three double-blind, placebo-controlled trials have been conducted showing promising results for the selective serotonin reuptake inhibitors (SSRIs) sertraline and fluoxetine, as well as for moclobemide, a reversible inhibitor of monoamine oxidase A.

Circadian rhythm phase advance with dawn simulation treatment for winter depression

A naturalistic pattern of dawn simulation (93 min, 0.001-250 lux) delivered to sleeping patients with winter depression has clinical efficacy similar to postawakening bright light therapy. The authors tested the circadian phase-shifting capacity of the dawn signal in a placebo-controlled, randomized 3-week field trial using 4 photic or nonphotic comparators: 30-min, 10,000-lux bright light therapy; a 13-min, 250-lux light pulse at the end of sleep; and high- and low-density negative air ionization timed to match the dawn. Bright light and dawn treatments both produced average phase advances of ~30 min, while the pulse and ion exposure had minimal effect. The authors conclude that very dim, incremental levels of light at the end of the night, with a dominant red component through eyelid filtering, facilitate circadian rhythm phase advances, possibly in conjunction with room light after awakening.

Effects of artificial dawn on sleep inertia, skin temperature, and the awakening cortisol response

The effect of artificial dawn during the last 30 min of sleep on subsequent dissipation of sleep inertia was investigated, including possible involvement of cortisol and thermoregulatory processes. Sixteen healthy subjects who reported difficulty with waking up participated in random order in a control and an artificial dawn night. Sleep inertia severity was measured by subjective ratings of sleepiness and activation, and by performance on an addition and a reaction time task measured at 1, 15, 30, 45, 60, and 90 min after waking up at habitual wake up time at workdays. At all intervals, saliva samples were collected for cortisol analysis. Sleep electroencephalogram was recorded during the 30 min prior to waking up; core body temperature and skin temperatures were recorded continuously until 90 min after waking up. Subjective sleepiness was significantly decreased and subjective activation increased after waking up in the artificial dawn condition as compared with control, in which lights were turned on at waking up. These effects can be explained by effects of artificial dawn on skin temperature and amount of wakefulness during the 30 min prior to the alarm. Artificial dawn accelerated the decline in skin temperature and in the distal-to-proximal skin temperature gradient after getting up. No significant effects of artificial dawn on performance, core body temperature, and cortisol were found. These results suggest that the physiology underlying the positive effects of artificial dawn on the dissipation of sleep inertia involves light sleep and an accelerated skin temperature decline after awakening.

Melatonin and its relevance to jet lag

Jet lag is a disorder in which body rhythms are out of phase with the environment because of rapid travel across time zones. Although it often produces minor symptoms it can cause serious problems in those who need to make rapid critical decisions including airline pilots and business travelers. In this article the authors review basic knowledge underlying the body clock, the suprachiasmatic nucleus (SCN) of the hypothalamus, and the manner in which it regulates the sleep/wake cycle. The regulation of melatonin by the SCN is described together with the role of the melatonin receptors which are integral to its function as the major hormonal output of the body clock. Several factors are known that help prevent and treat jet lag, including ensuring adequate sleep, appropriate timing of exposure to bright light and treatment with melatonin. Because travel can cross a variable number of time zones and in two different directions, recommendations for treatment are given that correspond with these different types of travel. In addition to use of bright light and melatonin, other factors including timed exercise, timed and selective diets and social stimuli deserve study as potential treatments. Moreover, new melatonin agonists are currently under investigation for treatment of jet lag.

Light therapy for seasonal and nonseasonal depression: efficacy, protocol, safety, and side effects

Bright light therapy for seasonal affective disorder (SAD) has been investigated and applied for over 20 years. Physicians and clinicians are increasingly confident that bright light therapy is a potent, specifically active, nonpharmaceutical treatment modality. Indeed, the domain of light treatment is moving beyond SAD, to nonseasonal depression (unipolar and bipolar), seasonal flare-ups of bulimia nervosa, circadian sleep phase disorders, and more. Light therapy is simple to deliver to outpatients and inpatients alike, although the optimum dosing of light and treatment time of day requires individual adjustment. The side-effect profile is favorable in comparison with medications, although the clinician must remain vigilant about emergent hypomania and autonomic hyperactivation, especially during the first few days of treatment. Importantly, light therapy provides a compatible adjunct to antidepressant medication, which can result in accelerated improvement and fewer residual symptoms.

Adjunctive strategies in the treatment of refractory bipolar depression: clinician options in the absence of a systematic database

Multiple approaches to enhancing antidepressant treatment response in bipolar depression are available and should, in many instances, be explored despite a lack of definitive controlled trial literature supporting their efficacy. Given that the morbidity of depression is three times greater than mania in bipolar illness, a range of treatment approaches to this phase of illness should be pursued. This paper highlights the preliminary evidence of efficacy versus side effects, tolerability, and safety in order to suggest an overall provisional utility grade for each well-studied to highly-experimental option. Given the general paucity of evidence to support efficacy or to sequence different approaches for augmenting treatment of bipolar depression, it is critical that patient and physician adopt a systematic and, preferably, daily rating approach to the assessment of benefit for a given patient of each strategy contemplated. The goal is to achieve and maintain remission of depressive symptoms and associated comorbidities, which is often not accomplished using primary mood stabilizer treatments alone, or in combination; thus, an active clinical approach to augmentation strategies is indicated even when the literature provides only highly preliminary guidance.

Association of morning illumination and window covering with mood and sleep among post-menopausal women

The antidepressant and sleep-promoting effects of light exposure might be useful for treating age-related mood and sleep disorders. In view of recent evidence suggesting beneficial effects of morning light, this study examined the associations of mood and sleep with morning light exposure, 24 h environmental illumination, and the degree to which the volunteers' bedroom windows were covered in the morning. We examined 459 postmenopausal women participating an ancillary study of the Women's Health Initiative conducted at the University of California, San Diego Clinical Center, San Diego, CA, USA. At baseline, volunteers completed a 4-week sleep-recall questionnaire. Volunteers were then assessed for 5-7 days in their home environments with actigraphic wrist monitors. During home recording, self-reported mood was assessed. Morning illumination during the first 4 h after arising, 24-h illumination mesor (cosine-fitted mean), and illumination acrophase (cosine-fitted peak time) were calculated. Sleep was scored each night using validated wrist actigraphic methods. A sleep diary was completed each morning. During two 24-h periods, urine was collected approximately every 2 h during wakefulness and following any voidings during the sleep period. Cosine-fitting established the acrophase of urinary 6-sulfatoxymelatonin (aMT6s) excretion. Morning illumination and 24-h illumination were modestly associated with better mood and sleep. Associations of light with mood and sleep were consistently greater for subjects whose body clocks were delayed relative to the group median. Less morning window covering in the subjects' bedrooms was associated with more morning light and less depressed mood. The results suggest that both morning and 24-h light exposure may be beneficial for older adults.

The effect of dawn simulation on the cortisol response to awakening in healthy participants

Bright light exposure after awakening has been shown to elevate cortisol levels in healthy participants. The present study examined the effect of dawn simulation (a treatment for seasonal affective disorder) on the cortisol response to awakening and mood. Twelve healthy participants were supplied with a dawn simulator (The Natural Alarm Clock, Outside In, Cambridge Ltd), a bedside light that increases in intensity prior to awakening to approximately 250 lux over 30 mins when an audible alarm sounds. A counterbalanced study was performed on 4 consecutive normal weekdays, two of which were control days (no dawn simulation) and two experimental (dawn simulation). Saliva samples were taken immediately on awakening then at 15, 30 and 45 minutes post awakening on all 4 study-days. Total cortisol production during the first 45 mins after awakening was found to be significantly higher in the experimental condition than in the control condition. Participants also reported greater arousal in the experimental condition and there was a trend for an association between increased arousal and increased cortisol secretory activity under dawn simulation. This study provides supportive evidence for the role of light and the suprachiasmatic nucleus in the awakening cortisol response.

Effect of simulated dawn on quality of sleep--a community-based trial

BACKGROUND

Morning light exposure administered as simulated dawn looks a promising method to treat Seasonal Affective Disorder, but it may moreover help with resetting the inaccurate organisation of body clock functions relative to sleep occurring in winter among people in general. Disturbances in sleep patterns are common and may compromise wellbeing even in the short term. Our hypothesis was that simulated dawn could improve the subjective quality of sleep during winter.

METHODS

A community-based trial with 100 volunteer subjects provided with dawn simulators. Study period lasted for eight weeks, and subjects used the dawn simulators for two weeks at a time, each subject acting as his own control (ABAB-design). Main outcome measure was subjective quality of sleep recorded each morning with Groningen Sleep Quality Scale.

RESULTS

77 subjects completed the trial. Quality of sleep improved while subjects were using dawn simulator-devices (p = 0.001). The treatment became beneficial after six days' use of dawn simulator, but the effect did not last after the use was ceased.

CONCLUSION

Dawn simulation may help to improve the subjective quality of sleep, but the benefits are modest. Further research is needed to verify these findings and to elucidate the mechanism by which dawn simulation acts on the sleep-wake pattern.

Twilights widen the range of photic entrainment in hamsters

The range of entrainment of the circadian rhythm of locomotor activity was compared in four groups of Syrian hamsters (eight animals per group) initially exposed to daily light-dark (LD) cycles with either abrupt transitions between light and darkness (LD-rectangular) or simulated twilights (LD-twilight). Lighting was provided by arrays of white light-emitting diodes; daytime illuminance (10 lux) and the total amount of light emitted per day were the same in the two conditions. The period (T) of the LD cycles was then gradually increased to 26.5 h or gradually decreased to 21.5 h, at the rate of 5 min/day. Under LD-rectangular, the upper and lower limits of entrainment were 25.0 to 25.5 h and 22.0 to 22.5 h, respectively, whereas under LD-twilight, 50% of the animals exposed to the lengthening cycles were still entrained at T = 26.5 h and 50% of those exposed to the shortening cycles were still entrained at T = 21.5 h. In a second experiment, two groups of hamsters were exposed to fixed T = 25 h LD-rectangular (n = 15) or LD-twilight cycles (n = 7). Only 33% of the animals entrained in LD-rectangular, whereas 86% of the animals entrained in LD-twilight. Free-running periods in constant darkness were longer following successful entrainment to T = 25 h but did not differ between the animals that entrained to LD-rectangular and those that entrained to LD-twilight. The widening of the range of entrainment observed in LD-twilight indicates that twilight transitions increase the strength of the LD zeitgeber. In LD-twilight, successful entrainment to T = 26.5 h was accompanied by an expansion of activity time to 16.52+/-1.22 h, with activity onsets preceding mid-dusk by 12.56+/-2.15 h. Together with earlier data showing similar phase response curves for hour-long dawn, dusk, and rectangular light pulses, these results suggest that the effect of twilights on the range of entrainment may involve parametric rather than nonparametric mechanisms.

Is dawn simulation effective in ameliorating the difficulty awakening in seasonal affective disorder associated with hypersomnia?

BACKGROUND

Patients with winter depression, (seasonal affective disorder, SAD) frequently complain of difficulty awakening in the morning. Dawn simulation has been found effective in treating SAD, but its effect on difficulty awakening has not been assessed.

METHODS

Fifty medication-free patients with SAD associated with hypersomnia were randomized to receive either 1 week of dawn simulation (250 lux) or a dim (0.2-2 lux) placebo signal. The patients assessed their level of drowsiness upon awakening during the baseline week and during the treatment week using the Stanford sleepiness scale (SSS). A psychiatrist rated difficulty awakening after the baseline week and after the treatment week.

RESULTS

Dawn simulation lowered both the difficulty awakening score (P<0.05) and the SSS score (P<0.05) compared to the placebo dawn signal.

LIMITATIONS

Replication is necessary. No biological markers of circadian phase were measured.

CONCLUSIONS

Compared to a placebo condition, dawn simulation appears effective in decreasing both prospectively assessed morning drowsiness and retrospectively assessed difficulty awakening. The symptom of difficulty awakening is consistent with the phase delay hypothesis of SAD. Assessment of difficulty awakening could prove useful in the evaluation of SAD.

Bright-light mask treatment of delayed sleep phase syndrome

We treated delayed sleep phase syndrome (DSPS) with an illuminated mask that provides light through closed eyelids during sleep. Volunteers received either bright white light (2,700 lux, n = 28) or dim red light placebo (0.1 lux, n = 26) for 26 days at home. Mask lights were turned on (< 0.01 lux) 4 h before arising, ramped up for 1 h, and remained on at full brightness until arising. Volunteers also attempted to systematically advance sleep time, avoid naps, and avoid evening bright light. The light mask was well tolerated and produced little sleep disturbance. The acrophase of urinary 6-sulphatoxymelatonin (6-SMT) excretion advanced significantly from baseline in the bright group (p < 0.0006) and not in the dim group, but final phases were not significantly earlier in the bright group (ANCOVA ns). Bright treatment did produce significantly earlier phases, however, among volunteers whose baseline 6-SMT acrophase was later than the median of 0602 h (bright shift: 0732-0554 h, p < 0.0009; dim shift: 0746-0717 h, ns; ANCOVA p = 0.03). In this subgroup, sleep onset advanced significantly only with bright but not dim treatment (sleep onset shift: bright 0306-0145 h, p < 0.0002; dim 0229-0211 h, ns; ANCOVA p < .05). Despite equal expectations at baseline, participants rated bright treatment as more effective than dim treatment (p < 0.04). We conclude that bright-light mask treatment advances circadian phase and provides clinical benefit in DSPS individuals whose initial circadian delay is relatively severe.

Dawn simulation and bright light in the treatment of SAD: a controlled study

BACKGROUND

Some small controlled studies have found that dawn simulation is effective in treating seasonal affective disorder (SAD). With a larger sample size and a longer duration of treatment, we compared dawn simulation with bright light therapy and a placebo condition in patients with SAD.

METHOD

Medication-free patients with SAD were randomly assigned to one of three conditions: bright light therapy (10,000 lux for 30 min, from 6:00 AM to 6:30 AM), dawn simulation (1.5 hour dawn signal from 4:30 AM to 6:00 AM peaking at 250 lux), and a placebo condition, a dim red light (1.5 hour dawn signal from 4:30 am to 6:00 AM peaking at 0.5 lux.) Over the subsequent 6 weeks, the subjects were blindly rated by a psychiatrist using the Structured Interview Guide for the Hamilton Depression Rating-Seasonal Affective Disorder Version (SIGH-SAD). We modeled the profiles of the remissions (SIGH-SAD < or = 8) and response (> or =50% decrease in SIGH-SAD) to treatment over time using Cox proportional hazards models.

RESULTS

The sample consisted of 95 subjects who were randomized to the three conditions: bright light (n = 33), dawn simulation (n = 31) and placebo (n = 31). Dawn simulation was associated with greater remission (p <.05) and response (p <.001) rates compared to the placebo. Bright light did not differ significantly from the placebo. Dawn simulation was associated with greater remission (p <.01) and response (p <.001) rates compared to the bright light therapy. The mean daily hours of sunshine during the week before each visit were associated with a significant increase in likelihood of both remission (p <.001) and response (p <.001).

CONCLUSIONS

Dawn simulation was associated with greater remission and response rates compared to the placebo and compared to bright light therapy. The hours of sunshine during the week before each assessment were associated with a positive clinical response.

Is seasonal affective disorder a disorder of circadian rhythms?

Seasonal affective disorder (SAD) is a form of depression that starts in the fall and ends in the spring. This article reviews existing theories about the relationship between circadian rhythms and the disorder. Recent research indicates that as with pharmacologic antidepressants, at least 2-4 weeks are needed to demonstrate the effectiveness of bright-light therapy compared to placebo. The response to such treatment is strongest with precisely timed light exposure: treatment is optimal during the morning hours when the circadian system is susceptible to phase advance. Such clinical improvement is correlated with the magnitude of the phase shift induced. These observations suggest a model of circadian function in SAD and provide important guidelines for its treatment.

The human circadian pacemaker can see by the dawn's early light

The authors' previous experiments have shown that dawn simulation at low light intensities can phase advance the circadian rhythm of melatonin in humans. The aim of this study was to compare the effect of repeated dawn signals on the phase position of circadian rhythms in healthy participants kept under controlled light conditions. Nine men participated in two 9-day laboratory sessions under an LD cycle 17.5:6.5 h, < 30:0 lux, receiving 6 consecutive daily dawn (average illuminance 155 lux) or control light (0.1 lux) signals from 0600 to 0730 h (crossover, random-order design). Two modified constant routine protocols before and after the light stimuli measured salivary melatonin (dim light melatonin onset DLMOn and offset DLMOff) and rectal temperature rhythms (midrange crossing time [MRCT]). Compared with initial values, participants significantly phase delayed after 6 days under control light conditions (at least -42 min DLMOn, -54 min DLMOff, -41 min MRCT) in spite of constant bedtimes. This delay was not observed with dawn signals (+10 min DLMOn, +2 min DLMOff, 0 min MRCT). Given that the endogenous circadian period of the human circadian pacemaker is slightly longer than 24 h, the findings suggest that a naturalistic dawn signal is sufficient to forestall this natural delay drift. Zeitgeber transduction and circadian system response are hypothesized to be tuned to the time-rate-of-change of naturalistic twilight signals.

Gradual changes in environmental light intensity and entrainment of circadian rhythms

Environmental light-dark alternation is the most potent zeitgeber of circadian rhythm in most organisms. Responses of the circadian system to brief light pulses and rectangular light-dark cycles have been extensively studied in many species. Under natural conditions, however, light intensity changes gradually throughout the day, and light-responsive neurons in the mammalian circadian system have response characteristics suitable for detection of gradual changes in light intensity during twilight. Several researchers have examined rhythm-entraining properties of artificial twilight and fluctuating light intensity cycles, and have stressed the importance of gradual transition between light and darkness for entrainment of circadian rhythms. But many questions about photic entrainment still remain to be answered. Further studies on entrainment of circadian rhythms will be useful for prevention and treatment of circadian rhythm-related disorders.

Phase advance after one or three simulated dawns in humans

A specially designed apparatus that can simulate the waveform of the dawn or dusk signal at any latitude and any day of the year has been shown to phase shift the circadian pacemaker in rodents and primates at a fraction of the illuminance previously used. Until recently, it was considered that rather high illuminances or rather long exposure episodes to room light were necessary to phase shift human circadian rhythms. This experiment shows that, under controlled conditions of a modified constant routine protocol, a single dawn signal is sufficient to phase advance the timing of the onset of secretion of the pineal hormone melatonin. The significant phase advance of salivary melatonin of 20 minutes, which is enhanced to 34 minutes after three consecutive dawn signals, is small, but appears to be of sufficient magnitude to entrain the human circadian pacemaker, which has an endogenous period of about 24.2h.

Chronic fatigue syndrome and seasonal affective disorder: comorbidity, diagnostic overlap, and implications for treatment

This study aimed to determine symptom patterns in patients with chronic fatigue syndrome (CFS), in summer and winter. Comparison data for patients with seasonal affective disorder (SAD) were used to evaluate seasonal variation in mood and behavior, atypical neurovegetative symptoms characteristic of SAD, and somatic symptoms characteristic of CFS. Rating scale questionnaires were mailed to patients previously diagnosed with CFS. Instruments included the Personal Inventory for Depression and SAD (PIDS) and the Systematic Assessment for Treatment Emergent Effects (SAFTEE), which catalogs the current severity of a wide range of somatic, behavioral, and affective symptoms. Data sets from 110 CFS patients matched across seasons were entered into the analysis. Symptoms that conform with the Centers for Disease Control and Prevention (CDC) case definition of CFS were rated as moderate to very severe during the winter months by varying proportions of patients (from 43% for lymph node pain or enlargement, to 79% for muscle, joint, or bone pain). Fatigue was reported by 92%. Prominent affective symptoms included irritability (55%), depressed mood (52%), and anxiety (51%). Retrospective monthly ratings of mood, social activity, energy, sleep duration, amount eaten, and weight change showed a coherent pattern of winter worsening. Of patients with consistent summer and winter ratings (n = 73), 37% showed high global seasonality scores (GSS) > or = 10. About half this group reported symptoms indicative of major depressive disorder, which was strongly associated with high seasonality. Hierarchical cluster analysis of wintertime symptoms revealed 2 distinct clinical profiles among CFS patients: (a) those with high seasonality, for whom depressed mood clustered with atypical neurovegetative symptoms of hypersomnia and hyperphagia, as is seen in SAD; and (b) those with low seasonality, who showed a primary clustering of classic CFS symptoms (fatigue, aches, cognitive disturbance), with depressed mood most closely associated with irritability, insomnia, and anxiety. It appears that a subgroup of patients with CFS shows seasonal variation in symptoms resembling those of SAD, with winter exacerbation. Light therapy may provide patients with CFS an effective treatment alternative or adjunct to antidepressant drugs.

Case study: dawn simulation as maintenance treatment in a nine-year-old patient with seasonal affective disorder

After four winter seasons of successful treatment with light boxes, a 9-year-old patient with seasonal affective disorder refused to make further use of the light box. Instead he was treated with dawn simulation (a dim light administered just before waking up and gradually increased in intensity). The patient used dawn simulation therapy from October until mid-May, with an occasional variation of the maximum light intensity (100, 200, or 300 iux). The patient, his parents, and his teacher were all happy with this type of treatment.

Dawn simulation vs. lightbox treatment in winter depression: a comparative study

Dawn simulation, with gradually increasing bedside light in the morning, has shown promising results as an alternative to bright light treatment for winter depression. To compare these treatments, 61 out-patients with winter depression (20-70 years of age, 80% women) were randomized to receive either lightbox treatment with 1500-2500 lux white light for 2 h in the morning for 6 days on an out-patient basis (n=34), or dawn simulation treatment in their homes, with 60 or 90 min of light augmentation time to 100-300 lux, for 2 weeks (n=27). Patients' ratings of improvement on a visual analogue scale (correlating strongly with percentage reduction in an extended Montgomery-Asberg Depression Rating Scale (MADRS) score) at the end of treatment showed a mean of 40.0% (SD 27.7%) in the dawn simulation group and 57.4% (SD 29.9%) in the lightbox group (P=0.02). The majority of the patients in both groups maintained their improvement during a 9-week follow-up. Age, sex, current major depression or current use of antidepressants did not predict outcome in either group. No serious side-effects were observed.

The influence of ambient light and menstrual status on the moods of a nonclinical population of young women

OBJECTIVE

To study the influence of the daily variation in ambient light and menstrual status on mood fluctuation in a nonclinical population of young women.

METHODS

Women kept mood diaries (two per day) over a period of 32 days that straddled the spring equinox. One group believed the purpose of the study was to investigate women's moods are significantly elevated by light, and this elevation occurs irrespective of the subjects knowledge of the experimental purpose. No evidence for a depression of women's mood in the premenstruum was found, although women who claimed to suffer from premenstrual syndrome (PMS) showed more reversals of their mood during the 32 days records were kept.

CONCLUSIONS

The results highlight the fact that an individual's mood may be influenced by the levels of ambient light as well as the photoperiod.

MidnightSun: software for determining light exposure and phase-shifting schedules during global travel

The application of circadian principles has the potential to alleviate jet-lag in global travelers, but their application is hampered by the difficulty of determining light exposure along international flight routes. Computerized tools can solve this problem algorithmically. We have developed a program for Macintosh computers, called MidnightSun, which allows researchers to display ambient lighting conditions at any geographical location at any time of the year. The program contains a data base with the latitudes and longitudes of over 3000 airports. It calculates flight paths and durations, and prints a graphical itinerary indicating times of daylight during flights and layovers. Given a travel itinerary and a user-defined phase response curve (PRC) for light, it recommends light exposure times that may accelerate the reentrainment of circadian rhythms to new time zones and reduce the deleterious effects of jet-lag (depending on the efficacy of the PRC and the compliance of the traveler). Other potential applications include determining lighting protocols for photoperiodism experiments and providing data sets for mathematical circadian simulations under naturalistic lighting conditions.

Seasonal variation in human illumination exposure at two different latitudes

The authors measured ambient illumination exposure in healthy volunteers in San Diego, California (latitude 32 degrees 43' N, n = 30), and Rochester, Minnesota (latitude 44 degrees 1' N, n = 24), during each of the four quarters of the year, which were centered on the solstices and equinoxes. Subjects wore photosensors on their wrists and lapels (or foreheads while in bed) 24 h per day for an average of 5-6 days per quarter. The maximum of the two illumination readings was stored each minute. Annual average time spent per day in outdoor illumination (> or = 1000 lux) was significantly higher in San Diego than it was in Rochester (p < .04). Daily durations of illumination at or exceeding thresholds of 1, 10, 100, 1000, and 10,000 lux were highly seasonal in the sample as a whole (p < .01 at 1 lux, p < .0001 at other thresholds). Seasonal variation in outdoor illumination was far more pronounced in Rochester than it was in San Diego (interaction p < .001) but remained significant in San Diego (p < or = .03). Seasonal variation in indoor illumination was generally similar in the two cities. The median Rochester subject experienced illumination > or = 1000 lux for 2 h 23 min per day during summer and 23 min per day during winter. The corresponding times in San Diego were 2 h 10 min and 1 h 20 min. Neither age nor gender predicted illumination duration at any level. Both season and geographic location strongly influenced human illumination exposure, and behavior (choice of indoor vs. outdoor environment) was the most important mediating factor.

Treatment of seasonal affective disorder: a review

OBJECTIVE

To review the status of current treatment of seasonal affective disorder (SAD).

METHOD

Treatment studies of SAD published between January 1989 and March 1995 were identified using a computerized MEDLINE literature search. Additional citations were obtained from the reference sections of these articles. Studies included in this review were selected using operational methodologic criteria.

RESULTS

Many studies support the efficacy of bright light therapy using a fluorescent light box. The best studied protocol is > 2500 lux white light for 2 hours per day, but newer protocols using 10,000 lux for 30 minutes have comparable response rates. Studies of light visors and other head-mounted devices also report similar response rates, but have not yet shown superiority over putative control conditions. There are fewer medication studies in SAD, but controlled studies suggest that fluoxetine, d-fenfluramine and propranolol are effective. Other treatments such as dawn simulation require further study. No studies of psychological treatments for SAD were found. Many studies had methodologic limitations, including brief treatment periods, small sample sizes, and lack of replication, that limit the generalizability of findings.

CONCLUSION

There are several well-studied, effective treatments for SAD, including light therapy and medications. However, further research must be done to demonstrate sustained treatment response over time, to clarify the intensity-response relationship of light therapy, to clarify the role of light therapy and medications, and to assess combination treatments.

Dawn simulation compared with a dim red signal in the treatment of winter depression

In a randomized, parallel design, 19 patients with winter depression were treated with either a week of a white 1.5-hr dawn simulation peaking at 250 lux or a week of a red, 1.5-hr dawn signal peaking at 2 lux. The subjects were told that they would receive either a white or red dawn reaching in intensity that would be dimmer than standard bright light treatment. At the end of both the baseline week and the treatment week subjects were blindly assessed with the Hamilton Rating Scale for Depression (HDRS). Analysis of covariance was used to compare the two dawn treatments. The white, 1.5-hr, 250 lux dawn simulation resulted in significantly (p < 0.05) lower HDRS scores compared to the red, 1.5-hr, 2 lux dawn. This is the second controlled study which indicates that dawn simulation is an effective treatment for winter depression.