Treatment of seasonal affective disorder with green light and red light

Bright Light Therapy for Major Depressive Disorder in Adolescent Outpatients: A Preliminary Study

BACKGROUND

Bright light therapy (BLT) has not been well-studied in adolescents with major depressive disorder, particularly in outpatient settings.

METHODS

We conducted an 8-week clinical trial of BLT in adolescents recruited from a primary care practice with moderate to severe major depression. Acceptability and feasibility were defined by daily use of the light box and integration into daily routines. To assess treatment effects, we utilized the Short Mood and Feelings Questionnaire (SMFQ) and actigraphic sleep variables.

RESULTS

Of the nine enrolled adolescents, the rate of daily use of the light therapy box was 100% at week 2, 78% at week 4 (n = 7), and 67% at weeks 6 and 8 (n = 6). Participants were better able to integrate midday BLT compared to morning BLT into their day-to-day routines. Mean depression scores improved during the 2-week placebo lead-in (dim red light-DRL) and continued to show significant improvement through 6 weeks of BLT. Sleep efficiency increased significantly (p = 0.046), and sleep onset latency showed a trend toward a significant decrease (p = 0.075) in the BLT phase compared to the DRL phase.

CONCLUSION

Bright light treatment that was self-administered at home was feasible, acceptable, and effective for adolescent outpatients with depression. Findings support the development of larger, well-powered, controlled clinical trials of BLT in coordination with primary care.

Commercially Available Phototherapy Devices for Treatment of Depression: Physical Characteristics of Emitted Light

Objective:

The purpose of this study was to evaluate key physical properties of commercially available light devices for the treatment of seasonal or nonseasonal depression and to determine whether the devices met clinical criteria, derived from evidence‐based clinical guidelines, for generating adequate light at a reasonable distance, over a reasonable field of illumination, and with an adequate degree of user acceptability.

Methods:

Twelve manufacturers loaned or donated 24 light therapy devices: 16 light boxes, one light column, four light‐emitting diode beam devices, and three light visors. Each device was evaluated for spectral power distribution, light dispersion, subjective discomfort from glare, adequacy of diffusion, photopic illuminance (in lumens per square meter [lux]), melanopic illuminance relative to photopic illuminance (efficacy ratio), and blue light hazard relative to melanopic illuminance (protection ratio).

Results:

Physical properties of emitted light varied widely among devices. Only seven larger light boxes satisfied the three clinical criteria. Some devices advertised as “10,000‐lux” devices produced this intensity only at unreasonably close distances, over a restricted field, or with unacceptable glare or unevenness of illumination. Five other devices emitted light with physical properties whose efficacy is less supported by research, although these devices may be useful for some patients.

Conclusions:

These results should help clinicians identify appropriate devices for patients seeking light therapy for seasonal or nonseasonal depression. Device selection is key to ensuring that patients receive evidence‐supported doses of light.

Red white and blue - bright light effects in a diurnal rodent model for seasonal affective disorder

Despite the common use of bright light exposure for treatment of seasonal affective disorder (SAD), the underlying biology of the therapeutic effect is not clear. Moreover, there is a debate regarding the most efficacious wavelength of light for treatment. Whereas according to the traditional approach full-spectrum light is used, recent studies suggest that the critical wavelengths are within the range of blue light (460 and 484 nm). Our previous work shows that when diurnal rodents are maintained under short photoperiod they develop depression- and anxiety-like behavioral phenotype that is ameliorated by treatment with wide-spectrum bright light exposure (2500 lux at the cage, 5000 K). Our current study compares the effect of bright wide-spectrum (3,000 lux, wavelength 420- 780 nm, 5487 K), blue (1,300 lux, wavelength 420-530 nm) and red light (1,300 lux, wavelength range 600-780 nm) exposure in the fat sand rat (Psammomys Obesus) model of SAD. We report results of experiments with six groups of sand rats that were kept under various photoperiods and light treatments, and subjected to behavioral tests related to emotions: forced swim test, elevated plus maze and social interactions. Exposure to either intense wide-spectrum white light or to blue light equally ameliorated depression-like behavior whereas red light had no effect. Bright wide-spectrum white light treatment had no effect on animals maintained under neutral photoperiod, meaning that light exposure was only effective in the pathological-like state. The resemblance between the effects of bright white light and blue light suggests that intrinsically photosensitive retinal ganglion cells (ipRGCs) are involved in the underlying biology of SAD and light therapy.

Rate of switch from bipolar depression into mania after morning light therapy: A historical review

Light therapy (LT) is efficacious for bipolar depression with effect sizes equivalent to those in antidepressant pharmacotherapy trials. Patients with bipolar disorder (BD) show a 15-40% rate of manic switches during antidepressant drug treatment. The rate of manic switches during LT has never been estimated. We searched all the literature studies reporting effects of antidepressant LT in BD. 41 studies described 799 patients with BD treated with antidepressant LT, from among which 7 (0.9%) switched into mania and 11 (1.4%) switched into hypomania. The method of assessment of treatment-emergent symptoms significantly influenced the detection of switches into mania: 0% when no method was reported, 0.8% with clinical mental state examination, and 3% with rating scales (χ² = 14.805, d.f. 4, p = 0.005). The rate of switch increased to 18.8% when considering the 16 patients with rapid-cycling BD. Switches occurred independent of treatment modality (light intensity, duration, and circadian timing of administration). The available literature shows that the highest reported rate of switch from bipolar depression into mania after LT is closely similar to the 4% switch rate expected during the placebo treatment of BD, thus not justifying specific concerns when using this treatment option.

Effect of short-term colored-light exposure on cerebral hemodynamics and oxygenation, and systemic physiological activity

There is not yet a comprehensive view of how the color of light affects the cerebral and systemic physiology in humans. The aim was to address this deficit through basic research. Since cerebral and systemic physiological parameters are likely to interact, it was necessary to establish an approach, which we have termed "systemic-physiology-augmented functional near-infrared spectroscopy (SPA-fNIRS) neuroimaging." This multimodal approach measures the systemic and cerebral physiological response to exposure to light of different colors. In 14 healthy subjects (9 men, 5 women, age: [Formula: see text] years, range: 24 to 57 years) exposed to red, green, and blue light (10-min intermittent wide-field visual color stimulation; [Formula: see text] blocks of visual stimulation), brain hemodynamics and oxygenation were measured by fNIRS on the prefrontal cortex (PFC) and visual cortex (VC) simultaneously, in addition with systemic parameters. This study demonstrated that (i) all colors elicited responses in the VC, whereas only blue evoked a response in the PFC; (ii) there was a color-dependent effect on cardiorespiratory activity; (iii) there was significant change in neurosystemic functional connectivity; (iv) cerebral hemodynamic responses in the PFC and changes in the cardiovascular system were gender and age dependent; and (v) electrodermal activity and psychological state showed no stimulus-evoked changes, and there was no dependence on color of light, age, and gender. We showed that short-term light exposure caused color-dependent responses in cerebral hemodynamics/oxygenation as well as cardiorespiratory dynamics. Additionally, we showed that neurosystemic functional connectivity changes even during apparently stress-free tasks-an important consideration when using any of the hemodynamic neuroimaging methods (e.g. functional magnetic resonance imaging, positron emission tomography, and fNIRS). Our findings are important for future basic research and clinical applications as well as being relevant for everyday life.

Are short (blue) wavelengths necessary for light treatment of seasonal affective disorder?

Despite widely published speculation regarding a potential potency advantage of short-wavelength (blue-appearing) light for Seasonal Affective Disorder (SAD) treatment, there have been few systematic studies. Those comparing short-wavelength to broad-wavelength (white) light under actual clinical conditions suggest equivalent effectiveness. This multicenter, parallel-group design trial was undertaken to compare the effects of light therapy on SAD using blue (~465 nm) versus blue-free (595-612 nm) LED lights. Fifty-six medication-free subjects aged 21-64 years who met DSM-IV-TR criteria for recurrent major depression with winter-type seasonal pattern were enrolled in this blinded study at five participating centers between January and March 2012. Thirty-five subjects met the criteria for randomization to 30 min of either blue (~465 nm) or blue-free (595-612 nm) daily morning light therapy. Twenty-nine subjects completed the study; three subjects withdrew due to treatment-related adverse events, including migraines, and three withdrew for non-study-related reasons. The primary effectiveness variable was depression score (SIGH-ADS) after six weeks of daily light treatment. Secondary effectiveness variables included quality-of-life (QoL) and suicidality ratings. Using an intent-to-treat analysis, mean depression scores were different at baseline for the blue group (29 ± 5 versus 26 ± 5, p = 0.05 blue versus blue-free, respectively), and the initial score was used as a covariate. Baseline scores were not significantly different between treatment groups among those who completed the study, and no significant differences in depression scores were observed after 6 weeks (mean ± SD scores at 6 weeks: 5.6 ± 6.1 versus 4.5 ± 5.3, p = 0.74, blue versus blue-free, respectively). In addition, the proportion of subjects who met remission criteria, defined as a depression score ≤8, was not significantly different between the two groups (p = 0.41); among the 29 subjects who completed the study, 76% of subjects experienced remission by the end of the trial, which coincided with the beginning of spring. The QoL and suicidality ratings were also significantly improved from pre- to post-treatment, with no significant difference between treatments. No subject experienced worsening or non-improved symptoms over the 6-week trial. The main finding of this study is that subjects treated with blue light did not improve more than subjects treated with blue-free light; both showed substantial improvement on multiple measures. Failure to find differences may have resulted from methodological constraints, including a small sample size. Recruitment began mid-winter during an unusually mild season, and the trial was terminated earlier than planned by the study sponsor due to a failure to detect a difference. However, if confirmed in a larger randomized sample, these results suggest that blue wavelengths are not necessary for successful SAD treatment.

Light therapy for bipolar disorder: a case series in women

OBJECTIVES

To perform a dose-ranging safety and efficacy study of bright light therapy for depression in women with bipolar disorder (BD).

METHODS

Nine women with DSM-IV BD I or II in the depressed phase were exposed to 50 lux (illuminance at the receiving surface) red light for two weeks, after which they received 7,000 lux light therapy for two-week epochs of 15, 30 and 45 min daily. The Structured Interview Guide for the Hamilton Depression Rating Scale with Atypical Depression Supplement and the Mania Rating Scale were used to assess mood symptoms. Four patients received morning light and five patients received midday light.

RESULTS

Three of the four subjects treated with morning light developed mixed states. The fourth subject achieved a full, sustained response. To decrease the risk of inducing mixed episodes, we changed the time of light exposure to midday. Of the five women who received midday light therapy, two achieved full response and two showed early improvement but required a dose increase to sustain response. One woman remained depressed with 45 min of midday light but responded fully to a switch to morning light, 30 min daily.

CONCLUSIONS

Women with bipolar illness are highly sensitive to morning bright light treatment; the induction of mixed states is a substantial risk. Initiating treatment with a brief duration (15 min) of midday light for bipolar depression is advisable.

Light therapy for seasonal affective disorder with blue narrow-band light-emitting diodes (LEDs)

BACKGROUND

While light has proven an effective treatment for Seasonal Affective Disorder (SAD), an optimal wavelength combination has not been determined. Short wavelength light (blue) has demonstrated potency as a stimulus for acute melatonin suppression and circadian phase shifting.

METHODS

This study tested the efficacy of short wavelength light therapy for SAD. Blue light emitting diode (LED) units produced 468 nm light at 607 microW/cm2 (27 nm half-peak bandwidth); dim red LED units provided 654 nm at 34 microW/cm2 (21 nm half-peak bandwidth). Patients with major depression with a seasonal pattern, a score of > or =20 on the Structured Interview Guide for the Hamilton Depression Rating Scale-SAD version (SIGH-SAD) and normal sleeping patterns (routine bedtimes between 10:00 pm and midnight) received 45 minutes of morning light treatment daily for 3 weeks. Twenty-four patients completed treatment following random assignment of condition (blue vs. red light). The SIGH-SAD was administered weekly.

RESULTS

Mixed-effects analyses of covariance determined that the short wavelength light treatment decreased SIGH-SAD scores significantly more than the dimmer red light condition (F = 6.45, p = .019 for average over the post-treatment times).

CONCLUSIONS

Narrow bandwidth blue light at 607 microW/cm2 outperforms dimmer red light in reversing symptoms of major depression with a seasonal pattern.

Bright green light treatment of depression for older adults [ISRCTN69400161]

BACKGROUND

Bright white light has been successfully used for the treatment of depression. There is interest in identifying which spectral colors of light are the most efficient in the treatment of depression. It is theorized that green light could decrease the intensity duration of exposure needed. Late Wake Treatment (LWT), sleep deprivation for the last half of one night, is associated with rapid mood improvement which has been sustained by light treatment. Because spectral responsiveness may differ by age, we examined whether green light would provide efficient antidepressant treatment in an elder age group.

METHODS

We contrasted one hour of bright green light (1,200 Lux) and one hour of dim red light placebo (<10 Lux) in a randomized treatment trial with depressed elders. Participants were observed in their homes with mood scales, wrist actigraphy and light monitoring. On the day prior to beginning treatment, the participants self-administered LWT.

RESULTS

The protocol was completed by 33 subjects who were 59 to 80 years old. Mood improved on average 23% for all subjects, but there were no significant statistical differences between treatment and placebo groups. There were negligible adverse reactions to the bright green light, which was well tolerated.

CONCLUSION

Bright green light was not shown to have an antidepressant effect in the age group of this study, but a larger trial with brighter green light might be of value.

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.

Is there a dysfunction in the visual system of depressed patients?

BACKGROUND: The aim of the current study was to identify a possible locus of dysfunction in the visual system of depressed patients. MATERIALS AND METHODS: Fifty Major Depressive patients aged 21-60 years and 15 age-matched controls took part in the study The diagnosis was obtained with the SCAN v 2.0. The psychometric assessment included the HDRS, the HAS, the Newcastle Scales, the Diagnostic Melancholia Scale and the GAF scale. Flash Electroretinogram and Electrooculogram were performed in all subjects. The statistical analysis included ANCOVA, Student's t-test and Pearson Product Moment Correlation Coefficient were used. RESULTS: The Electro-oculographic findings suggested that all subtypes of depressed patients had lower dark trough and light peak values in comparison to controls (p < 0.001), while Arden ratios were within normal range. Electroretinographic recordings did not reveal any differences between patients and controls or between subtypes of depression. DISCUSSION: The findings of the current study provide empirical data in order to assist in the understanding of the international literature and to explain the mechanism of action of therapies like sleep deprivation and light therapy.

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).

Light therapy for seasonal affective disorder in primary care: randomised controlled trial

BACKGROUND

Studies of light therapy have not been conducted previously in primary care.

AIMS

To evaluate light therapy in primary care.

METHOD

Fifty-seven participants with seasonal affective disorder were randomly allocated to 4 weeks of bright white or dim red light. Baseline expectations for treatment were assessed. Outcome was assessed with the Structured Interview Guide for the Hamilton Depression Scale, Seasonal Affective Disorder Version.

RESULTS

Both groups showed decreases in symptom scores of more than 40%. There were no differences in proportions of responders in either group, regardless of the remission criteria applied, with around 60% (74% white light, 57% red light) meeting broad criteria for response and 31% (30% white light, 33% red light) meeting strict criteria. There were no differences in treatment expectations.

CONCLUSIONS

Primary care patients with seasonal affective disorder improve after light therapy, but bright white light is not associated with greater improvements.

Prophylactic treatment of seasonal affective disorder (SAD) by using light visors: bright white or infrared light?

BACKGROUND

Thirty-eight patients with SAD participated in a light visor study addressing two questions. 1. Can the development of a depressive episode be prevented by daily exposure to bright light started before symptom onset in early fall and continued throughout the winter? 2. Does the light have to be visible in order to have beneficial effects?

METHODS

Three groups participated in the study: I (n = 14) received bright white light (2500 lux); II, (n = 15) received infrared light (0.18 lux); III (n = 9, control group) did not receive any light treatment at all.

RESULTS

Infrared light is just as effective as bright white light. Both are more effective than the control condition.

CONCLUSIONS

Light visors can be effectively used to prevent the development of SAD. The fact that exposure to infrared light was as effective as exposure to bright white light questions the specific role of visible light in the treatment of SAD.

A controlled study of light therapy in women with late luteal phase dysphoric disorder

Previous studies suggest that light therapy, as used to treat seasonal affective disorder, may be beneficial for pre-menstrual depressive disorders. We conducted a six-menstrual cycle randomized, double-blind, counter-balanced, crossover study of dim vs. bright light therapy in women with late luteal phase dysphoric disorder (LLPDD). Fourteen women who met DSM-III-R criteria for LLPDD completed two menstrual cycles of prospective baseline monitoring of pre-menstrual symptoms, followed by two cycles of each treatment. During the 2-week luteal phase of each treatment cycle, patients were randomized to receive 30 min of evening light therapy using: (1) 10000 lx cool-white fluorescent light (active condition); or (2) 500 lx red fluorescent light (placebo condition), administered by a light box at their homes. After two menstrual cycles of treatment, patients were immediately crossed over to the other condition for another two cycles. Outcome measures were assessed at the mid-follicular and luteal phases of each cycle. Results showed that the active bright white light condition significantly reduced depression and pre-menstrual tension scores during the symptomatic luteal phase, compared to baseline, while the placebo dim red light condition did not. These results suggest that bright light therapy is an effective treatment for LLPDD.

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.

A controlled trial of light therapy for the treatment of pediatric seasonal affective disorder

OBJECTIVE

To evaluate the efficacy of light therapy for the treatment of pediatric seasonal affective disorder (SAD).

METHOD

28 children (aged 7 to 17 years) at two geographically distinct sites were enrolled in a double-blind, placebo-controlled, crossover trial of bright-light treatment. Subjects initially entered a week-long baseline period during which they wore dark glasses for an hour a day. They were then randomly assigned to receive either active treatment (1 hour of bright-light therapy plus 2 hours of dawn simulation) or placebo (1 hour of clear goggles plus 5 minutes of low-intensity dawn simulation) for 1 week. The treatment phase was followed by a second dark-glasses phase lasting 1 to 2 weeks. After this phase, the children received the alternate treatment. Response was measured using the parent and child versions of the Structured Interview Guide for the Hamilton Depression Rating Scale, Seasonal Affective Disorders version (SIGH-SAD).

RESULTS

Data were analyzed as change from baseline. SIGH-SAD-P total depression scores were significantly decreased from baseline during light therapy compared with placebo (one-way analysis of variance, rho = .009), and no differences were found between the placebo and control phases. Subscores of atypical and typical depression were also significantly decreased during the active treatment (rho = .004 and .028, respectively). A similar trend was noted with the SIGH-SAD-C, but this did not reach significance. At the end of the study, 78% of the parents questioned and 80% of the children questioned rated light therapy as the phase during which the child "felt best."

CONCLUSION

Light therapy appears to be an effective treatment for pediatric SAD.

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.

Ophthalmologic examination of patients with seasonal affective disorder, before and after bright light therapy

PURPOSE

We assessed the potential ocular hazards of bright light therapy for patients with seasonal affective disorder, after both short- and long-term treatment, and identified prospective patients with pre-existing ocular abnormalities.

METHODS

Fifty patients with seasonal affective disorder received daily exposure to artificial light in the morning or evening for 30 minutes at an illuminance level of 10,000 lux (irradiant dose, 0.016 J/cm2). Ophthalmologic examinations were performed before and after short-term treatment (two to eight weeks) and after three to six years of use during the fall and winter months. Over the four years of patient intake, the eye examination included subsets of the following tests: visual acuity, intraocular pressure, slit-lamp biomicroscopy, direct and indirect ophthalmoscopy, color vision, visual field, fundus photography, Amsler grid, ocular motility, pupillary reactions, contrast sensitivity, stereopsis, and the macular stress test.

RESULTS

No ocular changes were detected after short-term treatment. Long-term treatment (three to six years) of 17 patients, with cumulative exposure durations of 60 to 1,250 hours, also resulted in no ocular abnormalities.

CONCLUSIONS

Light therapy yields about 75% clinical remissions. It is effective as an antidepressant and appears safe for the eyes. Current knowledge is insufficient to specify any definite ocular contraindications for bright light therapy, although we recommend that patients with preexisting ocular abnormalities and those using photosensitizing drugs undergo treatment only with periodic ophthalmologic examination.

The molecular basis for winter depression

A pulse of light is capable of inducing the circadian phase-dependent gene expression in neurons. The phase or amplitude of the circadian rhythms can be modulated by critically timed exposures to light. A significant heritability for the light-induced responses has been observed in hamsters. In humans, light has been used for treatment of the light-dependent winter depressive disorder. A genetic predisposition for high responsiveness to light may occur in patients with winter depression. The altered gene expression induced by light may account for a unique sensitivity to light and mediate the anti-depressant effect of light treatment.

Dim versus bright red (light-emitting diode) light in the treatment of seasonal affective disorder

Forty-three subjects with seasonal affective disorder were randomly assigned to receive 2 weeks of treatment with either bright- (mean 4106 lx) or dim-light (mean 96 lx) therapy, using red light-emitting diode light sources, in a head-mounted unit. Defining response as a 50% reduction in the 21-item Hamilton Depression Rating Scale score to a post-treatment score of less than 8, there was no significant difference in response rate between patients receiving bright light (67%) as compared with patients receiving dim light (68%). Possible explanations for the similar response rate to 2 very different illuminances of red light are discussed.

Effects of light on T-cells in HIV-infected subjects are not dependent on history of seasonal affective disorder

In order to evaluate the effect of light on helper- and suppressor-T-cell counts in HIV-infected individuals, with and without a history of seasonal affective disorder (SAD), we treated 35 subjects with 45 min of light therapy in the morning, in a crossover design involving two 2 week treatment conditions: visible white light (half-peak band width, 530-620 nm; 10,000 lux) and visible red light (half-peak band width, 615-685 nm; 175 lux). We found small but significant differences between the two treatment conditions, with higher CD4 and CD8 levels during the white, as compared with the red, condition. There were no differences between baseline and treatment conditions. Both light treatment conditions were associated with significant mood improvements in the SAD, but not the non-SAD, subjects. There was no evidence that the higher cell counts seen under the bright light conditions were mediated by the effects of light on mood or on plasma cortisol levels. While the size of the light effect on T-cells renders questionable the potential therapeutic value of this treatment modality for HIV, the finding is of theoretical interest and is reassuring for those HIV-infected individuals who require light treatment for other reasons.

Effects of phototherapy on electrooculographic ratio in winter seasonal affective disorder

Low electrooculographic (EOG) ratios have been reported in patients with seasonal affective disorder (SAD). This study was undertaken to replicate these results and to consider the effects of light therapy on the EOG in SAD patients. Sixteen outpatients with SAD and 16 age-, sex-, and medication-matched control subjects had EOG testing before and after 1 week of light therapy during the winter. The EOG ratios in the SAD patients were only marginally lower than those in the normal control subjects. These differences persisted after light therapy. Although the slightly decreased EOG ratios in SAD patients might have resulted from an artifact of test variability, drowsiness, or other confounding factors, the difference between patients and control subjects raises the possibility of retinal abnormality in SAD.

Serotonin, carbohydrates, and atypical depression

At least three categories of atypical depression have been described. The hysteroid dysphoria is characterized by repeated episodes of depressed mood in response to feeling rejected, and a craving for sweets and chocolate. Two other issues are characterized by a cyclical occurrence of changes of mood and appetite, i.e., the late luteal phase dysphoric disorder (DSM-III-R, appendix), or "the premenstrual syndrome" (PMS), and the major depression with seasonal pattern (DSM-III-R), or seasonal affective disorder (SAD). The reactive mood changes are frequently accompanied by features as hypersomnia, lethargy and increased appetite, particularly with a preference for carbohydrates. Central serotonin pathways participate in the regulation of mood and behavioural impulsivity, and modulate eating patterns qualitatively and quantitatively. Depressives with PMS og SAD benefit, in general, from treatments with serotonin potentiating drugs, suggesting that brain serotonin plays a role in the pathophysiology. Ingestion of carbohydrates increases the plasma ratio of tryptophan to other large neutral amino acids in man and animal, and the serotonin synthesis in the rat brain. Based on these findings it has been suggested that the excessive carbohydrate intake by patients with PMS and SAD reflects a self-medication that temporarily relieves the vegetative symptoms via an increased central serotonergic activity.

Phototherapy with broad spectrum white fluorescent light: a comparative study

The principles of photobiology suggest that the antidepressant effect of phototherapy depends on the dose and spectrum of light. We investigated the effect of spectrum by comparing two broad spectrum fluorescent light sources with different spectral distributions. In a crossover design, 11 patients with seasonal affective disorder (SAD) were treated with broad spectrum fluorescent and cool white light for 7 days. Scores on the Hamilton Rating Scale for Depression were reduced from 22.5 to 8.1 with broad spectrum fluorescent light and from 23.5 to 8.8 with cool white light. The results suggest that both light sources are effective treatments.

The effects of ultraviolet-A wavelengths in light therapy for seasonal depression

Although light therapy is a recognized effective treatment for seasonal affective disorder (SAD), there has been little research into the critical wavelengths of light that produce the antidepressant effect. Previous studies found conflicting results for the importance of the ultraviolet (UV) spectrum in the therapeutic effect of light therapy. To assess the clinical effects of UV-A wavelengths (315-400 nm), we studied 33 depressed SAD patients diagnosed with structured interviews by DSM-IIIR criteria. Following a baseline week, patients underwent 2 weeks of 2500 lux light therapy for 2 h daily (06:00-08:00). Light therapy consisted of cool-white fluorescent light with the addition of a special UV-A fluorescent tube. Patients were randomized to wear glasses during light therapy that either blocked (UV-blocked condition) or passed (UV-A condition) wavelengths below 400 nm. Both treatments significantly reduced all depression ratings, but no differences were found between the UV-A and UV-blocked conditions. We conclude that the UV-A spectrum does not increase the antidepressant response of light therapy. Given the potential side effects of chronic UV exposure, clinical application of light therapy should use light sources that have the UV spectrum filtered.

Predictors of response to phototherapy in seasonal affective disorder

We examined data from 44 women with seasonal affective disorder (SAD) to determine whether any demographic, diagnostic, or symptomatic characteristics would be predictive of a favorable response to phototherapy. Preexistent hypersomnia was particularly associated with lessening of depression after phototherapy. In contrast to a report elsewhere, both "typical" and "atypical" depressive symptoms correlated with improvement after phototherapy.

Effects of green or white light for treatment of seasonal depression

Twelve subjects with winter depression were treated with equal quanta of green or white light in a randomized crossover study. Each treatment condition consisted of 2 hours of exposure each morning for 1 week, with at least 1 interventing week without treatment. Ratings made without knowledge of treatment condition were done before and after each condition. Both treatments significantly reduced depression ratings. White light was significantly more effective than green light in reducing endogenous symptoms, but not the "atypical" symptoms that are common features of winter depression. Furthermore, sequence of treatment conditions influenced antidepressant responses. Broad-band white light may be optimal for maximizing therapeutic response.