Bright light treatment of winter depression: morning versus evening light

Predictive utility of symptom measures in classifying anxiety and depression: A machine-learning approach

Major depressive disorder (MDD) and generalized anxiety disorder (GAD) are highly prevalent, co-occurring disorders with significant symptom overlap, posing challenges in accurately distinguishing and diagnosing these disorders. The tripartite model proposes that anxious arousal is specific to anxiety and anhedonia is specific to depression, though anxious apprehension may play a greater role in GAD than anxious arousal. The present study tested the efficacy of the Mood and Anxiety Symptom Questionnaire anhedonic depression (MASQ-AD) and anxious arousal (MASQ-AA) scales and the Penn State Worry Questionnaire (PSWQ) in identifying lifetime or current MDD, current major depressive episode (MDE), and GAD using binary support vector machine learning algorithms in an adult sample (n = 150). The PSWQ and MASQ-AD demonstrated predictive utility in screening for and identification of GAD and current MDE respectively, with the MASQ-AD eight-item subscale outperforming the MASQ-AD 14-item subscale. The MASQ-AA did not predict MDD, current MDE, or GAD, and the MASQ-AD did not predict current or lifetime MDD. The PSWQ and MASQ-AD are efficient and accurate screening tools for GAD and current MDE. Results support the tripartite model in that anhedonia is unique to depression, but inclusion of anxious apprehension as a separate dimension of anxiety is warranted.

Effects of COVID-19 lockdown on university students' anxiety disorder in Italy

The COVID-19 pandemic has highlighted the vulnerability of specific population sections, with regards to economic and work conditions, mental and physical well-being, and context-based factors, emphasizing the need for timely policy measures aimed at counteracting the Italian economic framework’s fragility—which poorly adapts to unexpected circumstances. Identifying the most vulnerable groups is, therefore, essential with a view to carrying out targeted measures. Concerning University, the economic downturn caused by COVID-19 could likely result in a decrease in enrollments to both the first and further years of study, with significant consequences on the future of students and the system as a whole. The class of students is of great interest, as it is made up of individuals differing from each other in many ways. Our investigation is aimed at observing anxiety levels filtering the perception of one’s anxiety state in a highly stressful time such as the pandemic from the usual anxiety levels. This evaluation allows us to evaluate the similarity of individual behaviors during the lockdown period with those from the previous period.

Numerical study of entrainment of the human circadian system and recovery by light treatment

Background

While the effects of light as a zeitgeber are well known, the way the effects are modulated by features of the sleep-wake system still remains to be studied in detail.

Methods

A mathematical model for disturbance and recovery of the human circadian system is presented. The model combines a circadian oscillator and a sleep-wake switch that includes the effects of orexin. By means of simulations, we characterize the period-locking zone of the model, where a stable 24-hour circadian rhythm exists, and the occurrence of circadian disruption due to both insufficient light and imbalance in orexin. We also investigate how daily bright light treatments of short duration can recover the normal circadian rhythm.

Results

It is found that the system exhibits continuous phase advance/delay at lower/higher orexin levels. Bright light treatment simulations disclose two optimal time windows, corresponding to morning and evening light treatments. Among the two, the morning light treatment is found effective in a wider range of parameter values, with shorter recovery time.

Conclusions

This approach offers a systematic way to determine the conditions under which circadian disruption occurs, and to evaluate the effects of light treatment. In particular, it could potentially offer a way to optimize light treatments for patients with circadian disruption, e.g., sleep and mood disorders, in clinical settings.

Psychogenic Equinovarus Caused by Dislocation of the Chopart Joint Complex

Patients with conversion disorder (CD) present with weakness or unexplained movement disorder that may evolve from inciting psychological events, but presentation with rigid deformity is rare. Only one case of CD presenting as foot deformity with atraumatic rigid psychogenic equinovarus has been reported previously. Here we describe a rare case of psychogenic equinovarus in a physically healthy 10-year-old boy. He had noticed left equinovarus deformity upon waking abruptly but had no history of preceding trauma and no relevant medical history. Computed tomography (CT) images revealed dislocation of the left Chopart joint complex, but clinical examination did not suggest an organic neurologic disorder. On further history taking, he reported that he was under psychological stress because of being required to play baseball against his will. When he was given permission to withdraw from this stressful situation, the equinovarus improved without the need for surgical invention. This report highlights the importance of early and accurate diagnosis of psychogenic equinovarus, so that unnecessary surgery can be avoided. This is the first report of psychogenic equinovarus caused by dislocation of the Chopart joint complex that was confirmed with CT.

Seasonality of blood neopterin levels in the Old Order Amish

Seasonal changes in non-human animals and seasonal affective disorder (SAD) in humans are associated with immune activation in winter relative to summer. We intended to measure seasonal variation in neopterin, a marker of cellular immunity, and its interactions with gender and seasonality of mood. We studied 320 Amish from Lancaster, PA, USA (men = 128; 40%) with an average age [Standard deviation (SD)] of 56.7 (13.9) years. Blood neopterin level was measured with enzyme-linked immunosorbent assay (ELISA). Seasonality was measured with Seasonal Pattern Assessment Questionnaire (SPAQ). Statistical analysis included analysis of covariance (ANCOVAs) and multivariate linear regression. We also investigated interactions of seasonal differences in neopterin with gender, seasonality scores and estimation of SAD diagnosis. We found a significantly higher neopterin level in winter than in summer (p = 0.006). There were no significant gender or seasonality interactions. Our study confirmed the hypothesized higher neopterin level in winter. A cross sectional design was our major limitation. If this finding will be replicated by longitudinal studies in multiple groups, neopterin could be used to monitor immune status across seasons in demographically diverse samples, even if heterogeneous in gender distribution, and degree of seasonality of mood.

Psychogenic nonepileptic seizures and movement disorders: A comparative review

PURPOSE OF REVIEW

Neurologic symptoms due to a psychogenic cause are frequently seen in clinical practice. Psychogenic nonepileptic seizures (PNES) and psychogenic movement disorders (PMD) are among the most common psychogenic neurologic disorders. PNES and PMD are usually investigated and managed separately by different neurology subspecialists. We review the main epidemiologic and clinical features of both PNES and PMD, aiming to highlight their similarities and differences and to see whether a common framework for these disorders exists.

RECENT FINDINGS

Data from the literature show that there is a profound overlap between PNES and PMD, which would argue for a larger unifying pathophysiology with variable phenotypic manifestations.

SUMMARY

Collaborative and integrated research among epileptologists, movement disorders experts, psychiatrists, psychologists, and physiotherapists may increase our collective knowledge about the pathophysiologic mechanisms of PNES and PMD and therefore improve outcomes for these patients.

Clinical applications of melatonin in circadian disorders

Chronobiological disorders and syndromes include seasonal affective disorder (SAD), total blindness, advanced and delayed sleep phase syndrome, jet lag, and shift work maladaptation. These disorders are treated by adjusting circadian phase, using appropriately timed bright light exposure and melatonin administration (at doses of 0.5 mg or less). In some cases, it may be necessary to measure internal circadían phase, using the time when endogenous melatonin levels rise.

Bright light treatment for high-anxious young adults: a randomized controlled pilot study

BACKGROUND

Available treatments for anxiety have limitations and/or side effects. The aim of this study was to examine the influence of bright light exposure as a treatment in high-anxious young adults.

METHODS

In an acute exposure study, participants (n = 33) were randomly assigned to 45  min of (1) bright light or (2) placebo. Participants then performed a 5-week study (n = 29). Following a 1-week baseline, participants were randomly assigned to 4 weeks of daily exposure to either (1) bright light (45  min/day) or (2) placebo treatment, initiated ≤1 hr after awakening. Before and after the experiment, clinical ratings were conducted with the Hamilton Anxiety Scale (HAM-A), Hamilton Depression Scale, and Clinical Global Impressions scale. Following each week, blood pressure, anxiety (Spielberger State-Trait Anxiety Inventory Y1), depression, mood, sleep, and side effects were assessed.

RESULTS

No significant treatment effect was found in the acute exposure study. Likewise, in the 5-week study, no significant treatment effect was found. However, bright light elicited marginally greater reductions in psychic symptoms of the HAM-A (P = .06) and other measures.

CONCLUSIONS

This pilot study provides little compelling evidence for an anxiolytic effect of bright light in high-anxious young adults.

Winter Depression: Integrating mood, circadian rhythms, and the sleep/wake and light/dark cycles into a bio-psycho-social-environmental model

The phase shift hypothesis (PSH) states that most patients with SAD become depressed in the winter because of a delay in circadian rhythms with respect to the sleep/wake cycle: According to the PSH, these patients should preferentially respond to the antidepressant effects of bright light exposure when it is scheduled in the morning so as to provide a corrective phase advance and restore optimum alignment between the circadian rhythms tightly coupled to the endogenous circadian pacemaker and those rhythms that are related to the sleep/wake cycle. Recent support for the PSH has come from studies in which symptom severity was shown to correlate with the degree of circadian misalignment: it appears that a subgroup of patients are phase advanced, not phase delayed; however, the phase-delayed type is predominant in SAD and perhaps in other disorders as well, such as non-seasonal unipolar depression. It is expected that during the next few years the PSH will be tested in these and other conditions, particularly since healthy subjects appear to have more severe symptoms of sub-clinical dysphoria correlating with phase-delayed circadian misalignment; critically important will be the undertaking of treatment trials to investigate the therapeutic efficacy of morning bright light or afternoon/evening low-dose melatonin in these disorders in which symptoms are more severe as the dim light melatonin onset (DLMO) is delayed with respect to the sleep/wake cycle (non-restorative sleep should also be evaluated, as well as bipolar disorder). The possibility that some individuals (and disorders) will be of the phase-advanced type should be considered, taking into account that the correct timing of phase-resetting agents for them will be bright light scheduled in the evening and/or low-dose melatonin taken in the morning. While sleep researchers and clinicians are accustomed to phase-typing patients with circadian-rhythm sleep disorders according to the timing of sleep, phase typing based on the DLMO with respect to the sleep/wake cycle may lead to quite different recommendations for the optimal scheduling of phase-resetting agents, particularly for the above disorders and conditions.

Melatonin and human chronobiology

With the development of accurate and sensitive assays for measuring melatonin in plasma and saliva, it has been possible to advance our understanding of human chronobiology. In particular, the dim light melatonin onset (DLMO) is expected to have an increasingly important role in the diagnosis of circadian phase disorders and their treatment with appropriately timed bright light exposure and/or low-dose melatonin administration. The phase angle difference (PAD) between DLMO and mid-sleep can be used as a marker for internal circadian alignment and may also be used to differentiate individuals who are phase advanced from those who are phase delayed (a long interval indicates the former and a short interval indicates the latter). To provide a corrective phase delay, light exposure should be scheduled in the evening and melatonin should be administered in the morning. To provide a corrective phase advance, light exposure should be scheduled in the morning and melatonin should be administered in the afternoon/evening. The study of patients with seasonal affective disorder (SAD), as well as individuals who are totally blind, has resulted in several findings of interest to basic scientists, as well as psychiatrists and sleep specialists.

Seasonal affective disorder and its prevention by anticipatory treatment with bupropion XL

BACKGROUND

Seasonal affective disorder (SAD) can cause significant distress and impairment. No antidepressant studies have previously attempted to prevent the onset of autumn-winter depression.

METHODS

Three prospective, randomized, placebo-controlled prevention trials were conducted on 1042 SAD patients, enrolled in autumn and treated while still well, across the northern US and Canada. Patients received either bupropion XL 150-300 mg or placebo daily by mouth from enrollment until spring and were then followed off medications for 8 additional weeks. Primary efficacy variables were end-of-treatment depression-free rates and survival distributions of depressive recurrence.

RESULTS

Despite a reported average of 13 previous seasonal depressive episodes, almost 60% of patients had never previously been treated for depression. Major depression recurrence rates during the three studies for bupropion XL and placebo groups were 19% versus 30% (p = 0.026), 13% versus 21% (p = 0.049), and 16% versus 31%; yielding a relative risk reduction across the three studies of 44% for patients taking bupropion XL. Survival analyses for depression onset also favored bupropion XL over placebo (p = .081, .057, and <.001).

CONCLUSIONS

It is possible to prevent recurrence of seasonal major depressive episodes by beginning bupropion treatment early in the season while patients are still well.

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.

Light treatment of mood disorders

In 1981, seven patients with nonseasonal depression were treated with bright white light in 1982, bright artificial light was used to treat a manic-depressive patient with a seasonal mood cycle. In the last 20 years, a plethora of studies have further defined the depressive populations, who are responsive to light treatment; the optimal timing, intensity, spectral frequency, and duration of treatment; its comparison with other pharmacological interventions; predictors of response; side-effect profiles; viable placebo-control conditions; alternative devices and forms of administration; potential mechanisms and anatomical pathways mediating light's physiological effects; and its application to other disorders and subsyndromaI states. These studies have been conducted across multiple countries with surprisingly consistent results. Further work is needed, as highlighted in this review, to clarify the specific mechanism of action in subtypes of depressive disorders and differential age and gender effects. Although the majority of work in this area is relatively new, it behooves the reader to remember that Solomon, almost 3000 years ago, wrote in Ecclesiastes: "Truly the light is sweet and a pleasant thing it is for the eyes to behold the sun" (11:7).

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.

Bright light therapy of subsyndromal seasonal affective disorder in the workplace: morning vs. afternoon exposure

OBJECTIVE

Bright light therapy in seasonal affective disorder (SAD) has been studied extensively. However, little attention has been given to subsyndromal seasonal affective disorder (SSAD) or the use of bright light in the workplace. Many patients using bright light boxes complain of the inconvenience of use. Much of this inconvenience involves the often-recommended early timing of the bright light therapy. Patients, who already have difficulty awakening, often have difficulty using the bright light therapy soon after awakening before going to work. If bright light could be used effectively in the workplace, the treatment would be more convenient; the improved convenience would probably improve compliance. In this study, we studied the effectiveness of bright light therapy in subjects with SSAD in the workplace, comparing morning bright light with afternoon bright light.

METHOD

Morning and afternoon bright light treatment (2500 lux) were compared in 30 subsyndromal seasonal affective disorder patients using the bright light therapy in the workplace. Hamilton Depression Ratings and subjective measures of mood, energy, alertness and productivity were assessed before and after 2 weeks of light therapy.

RESULTS

Both morning and evening bright light significantly decreased the depression ratings and improved the subjective mood, energy, alertness and productivity scores. However, there were no significant differences between the two times of administration of the bright light treatment. Both bright light treatments were well tolerated.

CONCLUSION

Bright light given in the workplace improves subjective ratings of mood, energy, alertness and productivity in SSAD subjects. Morning and afternoon bright lights resulted in similar levels of improvement.

Dose-response relationship of phototherapy for seasonal affective disorder: a meta-analysis

OBJECTIVE

The therapeutic effect of phototherapy for seasonal affective disorder (SAD) has been widely investigated. However, the antidepressant effect of various light intensities is inconclusive. The purpose of this study was to evaluate the dose-response relationship of phototherapy for SAD.

METHOD

A meta-analytical methodology was applied to 39 studies of phototherapy for SAD. The studies collected were screened for study quality by a threats-to-validity method before inclusion. The fixed-effects-model analysis of variance procedures were used for data analysis.

RESULTS

The results indicated that different light intensities produced different effects in reducing the typical symptoms, as measured by the Hamilton Depression Rating Scale, of patients with SAD. However, no significant differences in these effects were revealed between strong, medium and dim light in reducing the atypical symptoms of patients.

CONCLUSION

These findings showed that light intensity varied positively with the antidepressant effect for typical but not for atypical symptoms of SAD, suggesting that light intensity tended to have different therapeutic effects on the typical and atypical symptoms of SAD.

Pathophysiological mechanism of seasonal affective disorder

Despite the long history in medicine, the pathophysiological mechanism(s) of seasonal affective disorder (SAD) remain largely unknown. By employing a meta-analytic methodology, the authors of this study attempted to verify the validity of different pathophysiological mechanism(s) proposed for SAD. The findings showed that for phototherapy of medium light intensity, a combination of morning-evening therapy regime yielded the best therapeutic effect, and the antidepressant effect of the morning-evening light regime was superior to a single pulse of light administered at other times of day. Furthermore, the data showed that the antidepressant effect of a single pulse of light was similar for morning, midday, and evening light. These findings supported the photon-count hypothesis and refuted the proposed photoperiod, melatonin, and phase-shifting models of SAD.

Circadian temperature and cortisol rhythms during a constant routine are phase-delayed in hypersomnic winter depression

Circadian temperature, cortisol, and thyroid-stimulating hormone (TSH) rhythms during a constant routine were assessed in 6 female controls and 6 female patients with hypersomnic winter depression (seasonal affective disorder, SAD) before and after morning bright light treatment. After sleep was standardized for 6 days, the subjects were sleep-deprived and at bed rest for 27 hours while rectal temperature, cortisol, and TSH levels were assessed. The minimum of the fitted rectal temperature rhythm was phase-delayed in the SAD group compared to the controls 5:42 AM vs. 3:16 AM (p < .005); with bright light treatment, the minimum advanced from 5:42 AM to 3:36 AM (p = .06). The minimum of the cortisol rhythm was phase-delayed in the SAD group compared to the control group, 12:11 AM vs. 10:03 PM (P < .05); with bright light treatment, the minimum advanced from 12:11 AM to 10:38 PM (P = .06) [corrected]. The acrophase of the TSH rhythm was not significantly phase-delayed in SAD subjects compared to control, though the trend appeared to be toward a phase-delay (p = .07). After bright light therapy, the TSH acrophase was not significantly different in the SAD subjects; the trend was a phase-advance (p = .09). Overall, the data suggest that circadian rhythms are phase-delayed relative to sleep in SAD patients and that morning bright light phase-advances those rhythms.

Melatonin in light treatment of patients with seasonal and nonseasonal depression

Melatonin as a marker of circadian rhythm and the effect of bright light on melatonin were studied in 63 depressed patients, 42 with a seasonal pattern and 21 with a nonseasonal pattern. The patients were matched for age, time of treatment and severity of depression. Before light treatment, blood was sampled for melatonin and depression was clinically rated with the Comprehensive Psychopathological Rating Scale and Hamilton Depression Rating Scale. Two hours of light treatment, 350 cd/m2, was given daily for 10 days 0600 to 0800 or 1800 to 2000. Of the 42 patients with seasonal depression, 26 were treated with morning light and, 16 with evening light. The melatonin amplitude was significantly decreased by light, and the melatonin phase position was advanced by morning light and delayed by evening light. All patients except for 3 in each group changed in the expected direction. Although the patients with seasonal pattern had a more favorable outcome than patients with nonseasonal pattern, there was no difference in therapeutic outcome related to the baseline melatonin phase position. The hypothesis that the short term clinical effects of light therapy either in the morning or evening are related to pretreatment melatonin levels or alteration of melatonin amplitude or phase position was not supported in the study. There was also no significant difference between the seasonal and nonseasonal patients related to the degree of light suppression of melatonin and the rebound effect of serum melatonin levels following bright level exposure between 2200 and 2300 before regular light treatment.

Light treatment in seasonal and nonseasonal depression

Ninety patients with major depressive disorder were classified according to seasonal (n = 68, 50 women) or nonseasonal (n = 22, 17 women) pattern according to DSM-III-R. They were also clinically evaluated and rated before and after morning (0600-0800) or evening (1800-2000) light treatment for 10 days in a room with a luminance of 350 cd/m2 (approximately 1500 lx) at eye level. Mood ratings were performed using both the Comprehensive Psychopathological Rating Scale and the Hamilton Depression Rating Scale. Depressed patients with seasonal pattern improved significantly more than those with a nonseasonal pattern suggesting a specific nonplacebo effect of light treatment in depressed patients with seasonal pattern. There were no significant differences in outcome when light treatment was given in the morning or in the evening, and not between patients with and without atypical symptoms such as carbohydrate craving or increased appetite.

Light and biological rhythms

Chronobiology--derived from chronos (time), bios (life), and logos (study of)--is the objective description of biological time structures and plays an important role in medicine. Circadian rhythms regulate the behaviour, physiology and function of living organisms at many biochemical levels. The influence of the rhythmic manifestation of life may be shown in the constructive effects of growth, development and maturation and is named anachronobiology. In contrast catachronobiology denotes deleterious effects of time and rhythm which may lead to a diseased state. This article summarizes some new data about light as a synchronizer of biological rhythms. A time-keeper--biological clock--is used by the body for readjustment of rhythms when this is desirable. More recently, light has been used to adjust the biological clock following changes of circadian rhythms during shift work or jet lag occurring when flying from one time zone to another. Light may be used to treat depression, sleep disorders, menstrual dysregulations and other illnesses with disturbed circadian and seasonal rhythms. Examples of the importance of chronopharmacology (time-dependent changes in drug metabolism and drug effect) are also presented. New findings indicate that circadian oscillators are under genetic control; a light-influenced regulatory role for cellular immediate-early genes in circadian behaviour has been discovered. This suggests that light is of importance in regulation of macromolecular synthesis at all levels of the circadian system.

Psychiatric disorders and functional impairment in patients with persistent dizziness

OBJECTIVE

To determine the prevalence and predictors of psychiatric dizziness and to measure functional impairment associated with dizziness.

DESIGN

Consecutive outpatients with a chief complaint of dizziness.

SETTING

Four outpatient clinics at a military teaching hospital.

PATIENTS

100 dizzy patients and 25 control patients.

MEASUREMENTS AND MAIN RESULTS

Structured psychiatric interviews were conducted using the Diagnostic Interview Schedule, and functional status was assessed with the Sickness Impact Profile and the 20-item MOS (Medical Outcomes Study) Short-Form. Psychiatric disorders were a primary or contributory cause of dizziness for 40% of the dizzy patients. Compared with the control patients, the dizzy patients had a higher lifetime (46% vs 32%) as well as recent (37% vs 20%) prevalence of axis I disorders. The greatest differences were in disorders of depression and somatization. The dizzy patients had a higher lifetime prevalence (23% vs 8%) as well as recent history (11% vs 0%) of major depression or dysthymia. Also, somatization disorders were strikingly more common among the dizzy patients than among the control patients (37% vs 8%, p = 0.005), with the dizzy patients reporting more than three times as many psychiatric or unexplained physical symptoms (5.2 vs 1.5). Age < 40 years, related complaints of weakness or headaches, and dizziness provoked by hyperventilation or standing were independent predictors of psychiatric dizziness. The dizzy patients reported moderate functional impairment, which was most severe among those with psychiatric disorders.

CONCLUSIONS

Persistent dizziness is associated with increased functional impairment and psychiatric comorbidity, particularly depression and somatization. Moreover, psychiatric disorders aggravate the impairment that occurs with dizziness alone.

Morning and evening light treatment of seasonal affective disorder: response, relapse and prediction

Patients with seasonal affective disorder were randomly assigned to treatment with light in the morning (9.00-12.00 a.m.; n = 16; ML) or evening (6.00-9.00 p.m.; n = 11; EL). An intensive 24-day assessment procedure revealed the same response rates: 57% for ML, 50% for EL. During the rest of the winter season a relatively low relapse rate of 54% was found. No differences between ML and EL were found in the time course of depressed mood or fatigue. A significant negative correlation was found between diurnal variation during baseline and therapeutic response: the larger the diurnal variation the less the response, indicating a potential negative predictive value for this symptom. There were no significant correlations between baseline fatigue or hypersomnia and response.

Effects of imipramine on circadian rhythms in the golden hamster

The effects of the antidepressant imipramine on circadian organization were studied in wild-type and tau-mutant golden hamsters. Chronic imipramine treatment in doses ranging from 0-50 mg kg-1.day-1 depressed general activity and body temperature and caused a reduction in body weight but had no significant effect on circadian organization. Imipramine treatment did not affect the rate of reentrainment after a 6-h advance in the light-dark cycle, did not alter the advanced-phase angle of entrainment of tau-mutant hamsters, did not affect the free-running period of wild type hamsters, and did not alter the phase-response curve to light pulses. Because imipramine, a clinically effective antidepressant, did not have any measurable effect on the circadian system in these experiments, our results do not provide support for the hypothesis that the antidepressant action of imipramine is mediated by alterations in the circadian system.

Light therapy of depression; basal and clinical aspects

The effects of treatment with bright light in different forms of depressive conditions are described. The therapeutic mode rests on the hypothesis that they will normalize disturbed diurnal rhythms. The results have been more favourable when light has been given in the morning compared with in the evening, and in patients with seasonal depression rather than in those with non-seasonal illness.

The circadian rhythm of body temperature

This paper reviews the literature on the circadian rhythm of body temperature (CRT). The review starts with a brief discussion of methodological procedures followed by the description of known patterns of oscillation in body temperature, including ultradian and infradian rhythms. Special sections are devoted to issues of species differences, development and aging, and the relationships between the CRT and the circadian rhythm of locomotor activity, between the CRT and the thermoregulatory system, and between the CRT and states of disease. A section on the nervous control of the CRT is followed by summary and conclusions.

Morning or evening bright light treatment of winter depression? The significance of hypersomnia

In a randomized crossover design 19 patients with winter depression were treated with 7 days of bright morning light (6:00 to 8:00 AM) and 7 days of evening light (7:00 to 9:00 PM). Bright light in the morning reduced the Hamilton Depression Rating Scale score from 22.3 to 5.5; bright light in the evening decreased the Hamilton score from 21.0 to 12.2. Improvement in the depression as measured by the Hamilton Depression Rating scores was greater with morning light compared with evening lights. Hypersomnia was associated (p less than 0.05) with a superior response to morning light.