A placebo-controlled trial of light treatment for winter depression

"Shedding Light on Light": A Review on the Effects on Mental Health of Exposure to Optical Radiation

In relation to human health and functioning, light, or more specifically optical radiation, plays many roles, beyond allowing vision. These may be summarized as: regulation of circadian rhythms; consequences of direct exposure to the skin; and more indirect effects on well-being and functioning, also related to lifestyle and contact with natural and urban environments. Impact on mental health is relevant for any of these specifications and supports a clinical use of this knowledge for the treatment of psychiatric conditions, such as depression or anxiety, somatic symptom disorder, and others, with reference to light therapy in particular. The scope of this narrative review is to provide a summary of recent findings and evidence on the regulating functions of light on human beings’ biology, with a specific focus on mental health, its prevention and care.

The Efficacy of Light Therapy in the Treatment of Seasonal Affective Disorder: A Meta-Analysis of Randomized Controlled Trials

BACKGROUND

Bright light therapy (BLT) has been used as a treatment for seasonal affective disorder (SAD) for over 30 years. This meta-analysis was aimed to assess the efficacy of BLT in the treatment of SAD in adults.

METHOD

We performed a systematic literature search including randomized, single- or double-blind clinical trials investigating BLT (≥1,000 lx, light box or light visor) against dim light (≤400 lx) or sham/low-density negative ion generators as placebo. Only first-period data were used from crossover trials. The primary outcome was the post-treatment depression score measured by validated scales, and the secondary outcome was the rate of response to treatment.

RESULTS

A total of 19 studies finally met our predefined inclusion criteria. BLT was superior over placebo with a standardized mean difference of -0.37 (95% CI: -0.63 to -0.12) for depression ratings (18 studies, 610 patients) and a risk ratio of 1.42 (95% CI: 1.08-1.85) for response to active treatment (16 studies, 559 patients). We found no evidence for a publication bias, but moderate heterogeneity of the studies and a moderate-to-high risk of bias.

CONCLUSIONS

BLT can be regarded as an effective treatment for SAD, but the available evidence stems from methodologically heterogeneous studies with small-to-medium sample sizes, necessitating larger high-quality clinical trials.

Use of light therapy in German psychiatric hospitals

In order to determine the usage pattern of light therapy (LT), we performed a survey of all psychiatric hospitals in Germany in 1992. Our data reveal that 13% of all psychiatric hospitals perform LT and another 7% indicate their interest in this treatment. Stratification into different treatment facilities demonstrates that 57% of the psychiatric university hospitals use LT. The usage of LT started in Germany in 1982 and there was a sharp rise from 1987 onwards. The majority of hospitals (89% of those hospitals which use LT) use LT successfully for the treatment of seasonal affective disorder (SAD) and its subsyndromal form followed by non-SAD depression (68%). LT is used as monotherapy in 71% of SAD patients compared with 34% in non-SAD depression.

Depressive mood and circadian rhythms disturbances as outcomes of seasonal affective disorder treatment: A systematic review

BACKGROUND

The present systematic review was aimed at critically summarizing the evidence about interventions focused on circadian rhythms and mood symptoms in seasonal affective disorder (SAD).

METHODS

A systematic search of the electronic databases PUBMED, PsycINFO and Web of Science was conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement. Original papers reporting data about the effects of treatments on both mood and circadian rhythms disturbances in SAD patients were considered for inclusion. The quality of the evidence provided by the eligible studies was assessed using the Revised Cochrane Risk of Bias Tool (RoB 2.0) and the Cochrane Risk of Bias in Non-Randomized Studies of Interventions Tool (ROBINS-I).

RESULTS

Forty papers were deemed eligible for the systematic review. The evidence of treatment outcomes referring to circadian disturbances was not robust. Despite this, bright light therapy (BLT) demonstrates to phase-advance delayed rhythms and to improve sleep-wake disorders. As for mood symptoms, both BLT and selective serotonin reuptake inhibitors (SSRIs) show evidence of efficacy. The possible connection between improvements of mood symptoms and changes in circadian outcomes seems controversial.

LIMITATIONS

The included studies presented considerable methodological heterogeneity, small sample sizes and non-optimal sample selection.

CONCLUSIONS

The effectiveness of BLT in depressive symptoms and circadian disturbances of SAD was outlined by the present systematic review. The evidence about other biological and pharmacological treatments, although promising, should be replicated. A multifactorial etiopathogenesis could explain the heterogeneous clinical presentations of SAD and the complex link between mood and circadian symptoms.

Bright white light therapy in depression: A critical review of the evidence

BACKGROUND

Light therapy is an accepted treatment option, at least for seasonal affective disorder (SAD). Our aim was to critically evaluate treatment effects of bright white light (BWL) on the depressive symptoms in both SAD and non-seasonal depression.

METHODS

The systematic review was performed according to the PRISMA guidelines. PubMed, Embase, and PsycINFO were searched (December 1974 through June 2014) for randomized controlled trials published in peer-reviewed journals. Study quality was assessed with a checklist developed by the Swedish Council on Technology Assessment in Health Care. Only studies with high or medium quality were used in the meta-analyses.

RESULTS

Eight studies of SAD and two studies of non-seasonal depression met inclusion and quality criteria. Effects on SAD were estimated in two meta-analyses. In the first, week by week, BWL reached statistical significance only at two and three weeks of treatment (Standardized Mean Difference, SMD: -0.50 (-CI 0.94, -0.05); -0.31 (-0.59, -0.03) respectively). The second meta-analysis, of endpoint data only, showed a SMD of -0.54 (CI: -0.95, -0.13), which indicates an advantage for BWL. No meta-analysis was performed for non-seasonal depression due to heterogeneity between studies.

LIMITATIONS

This analysis is restricted to short-term effects of BWL measured as mean changes in scores derived from SIGH-SAD, SIGH-SAD self-report, or HDRS rating scales.

CONCLUSIONS

Most studies of BWL have considerable methodological problems, and the results of published meta-analyses are highly dependent on the study selection. Even though quality criteria are introduced in the selection procedures of studies, when the results are carefully scrutinized, the evidence is not unequivocal.

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.

Bright-light therapy in the treatment of mood disorders

Bright-light therapy (BLT) is established as the treatment of choice for seasonal affective disorder/winter type (SAD). In the last two decades, the use of BLT has expanded beyond SAD: there is evidence for efficacy in chronic depression, antepartum depression, premenstrual depression, bipolar depression and disturbances of the sleep-wake cycle. Data on the usefulness of BLT in non-seasonal depression are promising; however, further systematic studies are still warranted. In this review, the authors present a comprehensive overview of the literature on BLT in mood disorders. The first part elucidates the neurobiology of circadian and seasonal adaptive mechanisms focusing on the suprachiasmatic nucleus (SCN), the indolamines melatonin and serotonin, and the chronobiology of mood disorders. The SCN is the primary oscillator in humans. Indolamines are known to transduce light signals into cells and organisms since early in evolution, and their role in signalling change of season is still preserved in humans: melatonin is synthesized primarily in the pineal gland and is the central hormone for internal clock circuitries. The melatonin precursor serotonin is known to modulate many behaviours that vary with season. The second part discusses the pathophysiology and clinical specifiers of SAD, which can be seen as a model disorder for chronobiological disturbances and the mechanism of action of BLT. In the third part, the mode of action, application, efficacy, tolerability and safety of BLT in SAD and other mood disorders are explored.

A randomized, placebo-controlled trial of bright light and high-density negative air ions for treatment of Seasonal Affective Disorder

This study, conducted over the course of 5 years, assessed the antidepressant efficacy of two active treatments, bright white light and high-density negative ions, and the efficacy of two placebo treatments, dim red light and low-density negative ions, for Seasonal Affective Disorder (SAD). In a controlled laboratory setting, 73 women with SAD were exposed to one of the four treatment conditions over 12 consecutive days. Pretreatment expectation ratings did not significantly differ among the four treatment groups; however, expectation scores and treatment benefits were positively related. Over the course of treatment, subjects in all four groups showed significant score decreases on the Structured Interview Guide for the Hamilton Depression Rating Scale-Seasonal Affective Disorder Version-Self Rating (SIGH-SAD-SR) and on the Beck Depression Inventory (BDI). For raw scale scores, neither main effects of treatment nor interactions between treatment and time were significant. When remission outcome criteria were used, bright white light was significantly more effective than any of the other three treatments, and exposure to high-density negative ions was more effective than either of the two placebo conditions, although the difference was not significant.

Melatonin marks circadian phase position and resets the endogenous circadian pacemaker in humans

Measuring the dim light melatonin onset (DLMO) is a useful and practical way to assess circadian phase position in humans. As a marker for the phase and period of the endogenous circadian pacemaker, the DLMO has been shown to advance with exposure to bright light in the morning and to delay with exposure to bright light in the evening. This 'phase response curve' (PRC) to light has been applied in the treatment of winter depression, jet lag and shift work, as well as circadian phase sleep disorders. Exogenous melatonin has phase-shifting effects described by a PRC that is about 12 h out of phase with the PRC to light. That is, melatonin administration in the morning causes phase delays and in the afternoon causes phase advances. All of the circadian phase disorders that have been successfully treated with appropriately timed exposure to bright light can be treated with appropriately scheduled melatonin administration. Melatonin administration is more convenient and therefore may be the preferred treatment.

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).

A comparison of open treatment of seasonal major and minor depression with light therapy

BACKGROUND

Although several investigators have described a milder form of seasonal affective disorder (SAD), called subsyndromal SAD, little is known about the effect of light therapy in this group. The current study evaluates 3 weeks of open treatment with light therapy in SAD and subsyndromal SAD patients.

METHODS

Subjects with major or minor depression according to DSM-IV with a seasonal pattern were recruited during the winter of 1998-1999 from clinic patients and media advertising. Subjects were commenced on open treatment of morning light therapy, for 30 min daily using a new fluorescent light therapy unit that produced approximately 5,000 lux at a distance of 12 inches. The treatment lasted 3 weeks and at the end of the first and second week of treatment the duration of exposure could be increased to a maximum of 60 min at the discretion of the clinician. The Structured Interview Guide for the Hamilton Depression Rating Scale-SAD version (SIGH-SAD) was administered weekly to evaluate outcome. Response was defined in a variety of ways to reflect the fact that subsyndromal SAD subjects had milder symptoms.

RESULTS

Forty-six subjects entered treatment and 44 (SAD, n = 29, subsyndromal SAD, n = 15) completed at least 2 weeks. Response rates were generally similar in SAD subjects (64-69%) and subsyndromal SAD (40-67%) patients. There was a trend for longer exposure to be associated with better outcome.

CONCLUSIONS

Light therapy may be an effective treatment for subjects with both major and minor depression with a seasonal pattern. Optimal duration, for the light therapy unit used in this study, is likely 45-60 min daily.

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.

Nonverbal interpersonal attunement and extravert personality predict outcome of light treatment in seasonal affective disorder

We investigated whether personality and nonverbal interpersonal processes can predict the subsequent response to light treatment in seasonal affective disorder (SAD) patients. In 60 SAD patients, Neuroticism and Extraversion were assessed prior to light treatment (4 days with 30 min of 10.000 lux). From videotaped clinical interviews, the nonverbal interpersonal attunement (i.e. equalizing durations and frequencies of elements of behaviour between conversation partners) was registered for the patients' support seeking and the interviewers' support giving behaviour. The higher Extraversion and the more the patients and the interviewers got attuned over the interview, the more favourable the outcome of light treatment was. Hence, personality and nonverbal interpersonal processes may be involved in the response to light treatment in SAD.

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.

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.

Light mask 500 lux treatment for delayed sleep phase syndrome

1. Bright light exposure has been demonstrated as an effective treatment for circadian rhythm sleep disorders. Recent studies suggest that more moderate intensities of light might affect endogenous rhythms. A light mask treatment, using light applied through eyelids during sleep, was tested for Delayed Sleep Phase Syndrome. 2. The active light group (n = 5) received 500 lux light for 3 hours prior to awakening for 12 days. The placebo light group (n = 5) received 0.1 lux light with the same timing. Circadian rhythm phase was assessed from core body temperature and urinary 6-sulfatoxymelatonin measurements. The SIGH-SAD-SR mood scale was administered to assess mood. 3. There were slight trends toward a phase advance of the body temperature rhythm and a phase delay of the melatonin rhythm, and both groups reported anti-depressant benefits. However, no statistically significant effects of 500 lux light mask treatment were demonstrated compared with the placebo-light treatment. 4. More extensive studies will be required to clarify the factors of dose-response and phase-response.

Disorders of the sleep-wake cycle in adults

Adults have an intrinsic body clock which regulates a complex series of rhythms including sleep and wakefulness, fatigue and cognitive ability. This endogenous clock naturally runs more slowly than the solar day and is entrained to a 24-h rhythm primarily by the alternation of light and darkness. Jet lag, shift-work sleep disorder, and some of the chronic insomnias are caused by a temporal discrepancy of the body clock relative to the surrounding environment and social network. The underlying mechanisms and general management are described. Both bright light and melatonin therapy have potential in the management of these disorders. Traditionally, bright light therapy has been used to alleviate the depression associated with seasonal affective disorder. Melatonin has received much ill-formed publicity, it being claimed that it is a panacea and an 'antiageing' treatment. Both of these treatment approaches are reviewed.

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.

Will light brighten the future of the depressed patient?

The present explosive growth of interest in the therapeutic possibilities of exposure to light was triggered by a patient, Herbert Kern. He suffered from episodic depressive and manic complaints and discovered, by registering these over the years, a seasonal pattern in their occurrence. Discussions with scientists of the NIMH resulted in his participation in a bright light-treatment experiment when he was depressed in the winter of 1980-1981. He recovered. Next, the same group of investigators defined the criteria for a new syndrome, Seasonal Affective Disorder (SAD): a history of major affective disorder (according to the Research Diagnostic Criteria), at least two consecutive years in which the depressions have occurred during fall or winter and remitted in the following spring or summer, and the absence of any clear-cut seasonally changing psychosocial variable, such as work, stress and so on.

Seasonal affective disorder in Australia: is photoperiod critical?

OBJECTIVES

Seasonal affective disorder (SAD) is a variant of recurrent depression in which episodes are linked to a particular season, typically winter. SAD is understood as the extreme end of a continuum of seasonality in the general population. Photoperiod (the timing and duration of daylight) has been assumed to be aetiologically critical. The present research used a survey design to investigate the assumed centrality of photoperiod for SAD/seasonality in Australia. Two hypotheses were tested: that self-reported seasonality does not increase further from the equator and that seasonality does not stand alone from non-seasonal neurotic complaints.

METHOD

The sampling frame used was adult females on the Australian Twin Registry roll. A sample of 526 women residing across the latitudes of Australia responded to a survey based around the Seasonal Pattern Assessment Questionnaire (SPAQ). The SPAQ asks respondents to retrospectively report on season-related changes in mood and behaviour. The survey also contained three questionnaire measures of neurotic symptoms of anxiety and depression: the General Health Questionnaire (GHQ), the Community Epidemiological Survey for Depression (CES-D) and the State-Trait Anxiety Inventory-Trait (STAI-T).

RESULTS

Self-reported seasonality did not correlated with latitude (r = 0.01, NS). On the other hand, a substantial relationship was found between seasonality and each of the measures of non-seasonal complaints: GHQ (r = 0.35, p < 0.001); CES-D (r = 0.35, p < 0.001); and STAI-T (r = 0.30, p < 0.001).

CONCLUSIONS

Within the limitations of a design based on retrospective self-report, the findings of the present study suggest that the diathesis for SAD/seasonality may not be photoperiod-specific. At least in Australia, there is provisional support for the proposal that human seasonality may have a broader psychological component. The findings are discussed in terms of established research into normal mood, trait personality and non-seasonal depression.

L-tryptophan augmentation of light therapy in patients with seasonal affective disorder

OBJECTIVE

Up to one-third of patients with seasonal affective disorder (SAD) do not have a full response to light therapy. Given the evidence for serotonergic dysregulation in SAD, we examined the possible role of l-tryptophan as an augmentation strategy for nonresponders and partial responders to light therapy.

METHOD

Eligible drug-free patients meeting DSM-IV criteria for SAD were treated for 2 weeks using a standard morning light therapy regimen (10,000 lux cool-white fluorescent light for 30 minutes). Partial and nonresponders were treated for 2 weeks with open-label l-tryptophan (1 g 3 times daily) while light therapy was continued. Ratings at baseline and follow-up included the 29-item Structured Interview Guide for the Hamilton Depression Rating Scale, SAD version (SIGH-SAD) and the Clinical Global Impression (CGI) scale.

RESULTS

Sixteen patients began the l-tryptophan augmentation phase. Two patients discontinued medications within 3 days because of side effects. In the 14 patients completing treatment, the addition of l-tryptophan resulted in significant reduction of mean depression scores. Nine of 14 patients (64%) showed very good clinical responses to combined treatment and minimal side effects.

CONCLUSION

This open-label study suggests that l-tryptophan may be an effective augmentation strategy for those patients with SAD who show limited or poor response to bright ligh therapy. Further placebo-controlled studies are warranted to demonstrate efficacy.

Prediction of acute and late responses to light therapy from vocal (pitch) and self-rated activation in seasonal affective disorder

It was hypothesized that pre-treatment activation plays a role in the response to light therapy in Seasonal Affective Disorder (SAD). In 55 SAD patients (DSMIII-R) energetic and tense activation was assessed before light therapy via self-rating (AD-ACL) and voice sound characteristics (mean pitch and variation in pitch). These variables were studied in relation to the "acute" response to 4 days of light therapy (30 min, 10000 lux) and to a "late" response (11 (10) days after light therapy had stopped). Acute response was defined as the percent change in 3 times daily self-rated depressed mood (AMS) with respect to the average of 4 baseline days. "Late" response was defined as the percent change in HRSD or AMS scores between baseline and 11 (10) days after light therapy. It was found that patients having high pitched voices with small variation in this pitch benefitted more from light therapy than the patients with low pitch and large variation in pitch levels. This effect was only significant after the first day of light exposure. No other significant relations were found between baseline activation and acute or late responses to light therapy. Hence, light therapy seems to give extra comfort in "tense" patients, who become rapid responders to light therapy.

Effects of bright light on sleepiness, melatonin, and 25-hydroxyvitamin D(3) in winter seasonal affective disorder

Sixteen patients with winter seasonal affective disorder and 13 healthy controls were exposed to 3300 lx of cool-white fluorescent light for either 1 hour or 15 min in the morning for 2 weeks during the winter. Subjective sleepiness, melatonin concentration in saliva, and serum 25-hydroxyvitamin D(3) concentration were measured before and after the 2-week trial as well as the following summer when the patients were well. There were no significant differences in the baseline values between the patients and healthy subjects. No significant differences in the outcome measures were observed in the patients or the controls in the two groups of each after the trial. The exposure to bright light resulted in a significant decrease in subjective sleepiness early in the evening in the patients but not in the control subjects. The reduction of depressive symptoms was associated with the decrease in subjective sleepiness but not with the changes in the melatonin or vitamin D concentrations.

Chronobiotics--drugs that shift rhythms

A chronobiotic is defined and levels of action within the mammalian circadian pacemaker system, such as the retina, retinohypothalamic tract, geniculohypothalamic tract, suprachiasmatic nuclei, output and feedback systems are identified. Classes of drug that include the indoleamines, cholinergic agents, peptides, and benzodiazepines, which might act as chronobiotics within these levels, are evaluated. Particular emphasis is placed on the indole, melatonin (MLT). The clinical circumstances for use of chronobiotics in sleep disturbances of the circadian kind, such as jet lag, shift work, delayed sleep-phase syndrome, advanced sleep-phase syndrome, irregular and non-24-hr sleep-wake cycles, are described under reorganized headings of disorders of entrainment, partial entrainment, and desynchronization. Specific attention is given to the blind and the aged. Both human and animal studies suggest that MLT has powerful chronobiotic properties. MLT shows considerable promise as a prophylactic and therapeutic alternative or supplement to the use of natural and artificial bright light for resetting the circadian pacemaker. Throughout this discussion, the hypnotic and hypothermic versus the chronobiotic actions of MLT are raised. Finally, problems in the design of delivery systems for MLT are discussed.

Influence of phototherapy treatment duration for seasonal affective disorder: outcome at one vs. two weeks

Most previous phototherapy research has been conducted on trials of 1 week duration. This study compares response to phototherapy at weeks 1 and 2. All subjects (n = 26) were between 18 and 65 years and met Diagnostic and Statistical Manual of Mental Disorders, 3rd ed, revised, (DSM III-R) criteria for major depression, recurrent, seasonal pattern and had a Hamilton Depression Rating Scale score (HAM-D) > or = 20. A rater blinded to treatment schedule and study hypothesis repeated the HAM-D-31 1 and 2 weeks after baseline to assess treatment response to bright light. Response rates at week 1 defined by 50% reduction in HAM-D-31 and HAM-D-31 score < 8 were 62% and 27%, respectively. At week 2, however, 65% had a 50% reduction in HAM-D-31 and 62% had a HAM-D-31 < score 8 (chi-square = 6, p = 0.01). Four patients (15%) who were nonresponders at week 1 responded after 2 weeks. The results show a statistically different outcome after 2 weeks of treatment and suggest the necessity of longer trials of phototherapy.

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.

Observed behavior of patients with seasonal affective disorder and an interviewer predicts response to light treatment

We investigated whether observable behavior of seasonal affective disorder (SAD) patients and an interviewer during an interview before light treatment is related to the response to the light treatment. Different observed behavioral elements of 24 SAD patients and of 2 interviewers, assessed before light treatment, were reduced to "behavioral factors." Forward multiple regression analyses were applied to investigate whether these factors might predict the response to light therapy (3 h of bright light between 09:00 and 12:00 h or between 18:00 and 21:00 h on 5 consecutive days). In addition, it was investigated whether the interviewers' factors could be predicted from the patients' factors. Both patients' and interviewers' factors predicted the response to light treatment. Response-related factors of patients and interviewers were interrelated. The results suggest that behavioral processes may play a role in the mechanisms underlying the response to light treatment in SAD. They support the relevance of interpersonal theories in seasonal depression.

Light treatment for sleep disorders: consensus report. IV. Sleep phase and duration disturbances

Advanced and delayed sleep phase disorders, and the hypersomnia that can accompany winter depression, have been treated successfully by appropriately timed artificial bright light exposure. Under entrainment to the 24-h day-night cycle, the sleep-wake pattern may assume various phase relationships to the circadian pacemaker, as indexed, for example, by abnormally long or short intervals between the onset of melatonin production or the core body temperature minimum and wake-up time. Advanced and delayed sleep phase syndromes and non-24-h sleep-wake syndrome have been variously ascribed to abnormal intrinsic circadian periodicity, deficiency of the entrainment mechanism, or--most simply--patterns of daily light exposure insufficient for adequate phase resetting. The timing of sleep is influenced by underlying circadian phase, but psychosocial constraints also play a major role. Exposure to light early or late in the subjective night has been used therapeutically to produce corrective phase delays or advances, respectively, in both the sleep pattern and circadian rhythms. Supplemental light exposure in fall and winter can reduce the hypersomnia of winter depression, although the therapeutic effect may be less dependent on timing.

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 treatment for NASA shiftworkers

Intense artificial light can phase-shift circadian rhythms and improve performance, sleep, and well-being during shiftwork simulations. In real shiftworkers, however, exposure to sunlight and other time cues may decrease the efficacy of light treatment, and occupational and family responsibilities may make it impractical. With these considerations in mind, we designed and tested light-treatment protocols for NASA personnel who worked on shifted schedules during two Space Shuttle missions. During the prelaunch week, treatment subjects self-administered light of approximately 10,000 lux at times of day that phase-delay circadian rhythms. Treatment continued during the missions and for several days afterward. No treatment was administered to subjects in the control group. Treatment subjects reported better sleep, performance, and physical and emotional well-being than control subjects and rated the treatment as highly effective for promoting adjustment to their work schedules. Light treatment is both feasible and beneficial for NASA personnel who must work on shifted schedules during Space Shuttle missions.

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.

Relationship between cognitive sensitivity to (symbolic) light in remitted seasonal affective disorder patients and the onset time of a subsequent depressive episode

The role of cognitive sensitivity to light in the development of seasonal affective disorder (SAD, winter type) was studied by comparing 29 SAD patients during remission with 29 non-depressed controls matched by sex and age, and by relating measures for cognitive sensitivity of remitted SAD patients to the onset of a depressive episode during the following autumn/winter. To ensure that only cognitive processes were involved, the subjects were exposed to symbolic light. Three schematic drawings of ambiguous faces expressing different emotions were embedded in light or dark backgrounds for this purpose. The subjects rated the various facial expressions with respect to the degree of elation-sadness, rejection-invitation, and activation-sleepiness. SAD patients saw larger differences in activation between faces embedded in light and dark backgrounds than controls, perceiving less activation in faces with dark backgrounds. Furthermore, the larger the difference that SAD patients saw in invitation between faces with light and dark backgrounds, the earlier they became depressed in the subsequent autumn/winter. Only the SAD patients who became depressed early (before December 21) differed from controls in the perception of invitation. Results are interpreted within the framework of psychological theories on the development of depression and suggest that altered cognitive sensitivity of SAD patients to light plays a role in the development of depressive episodes.

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 morning light treatment on subjective sleepiness and mood in winter depression

The effects of morning light treatment on mood, subjective sleepiness and body temperature were investigated with 13 outpatients with winter depression and 13 healthy controls. Bright light for 1 h daily for 2 weeks resulted in a significant reduction in depression ratings and evening subjective sleepiness in the patients compared with the healthy controls. Even a short 15-min exposure to light daily produced these changes.

Effects of morning light treatment on subjective sleepiness and mood in winter depression

The effects of morning light treatment on mood, subjective sleepiness and body temperature were investigated with 13 outpatients with winter depression and 13 healthy controls. Bright light for 1 h daily for 2 weeks resulted in a significant reduction in depression ratings and evening subjective sleepiness in the patients compared with the healthy controls. Even a short 15-min exposure to light daily produced these changes.

The circadian rhythm of temperature during light treatment for winter depression

Circadian rhythm abnormalities have been implicated in winter seasonal affective disorder. We examined the circadian temperature rhythm of 22 patients with winter depression and 10 normal controls who had participated in various high-intensity light treatment experiments. We did not find abnormalities in the baseline phase or amplitude of the temperature rhythm in patients compared to controls. Nor did we find abnormalities in the phase-shifting response to morning light. There was some evidence that the "phase-delayed" half of the patients responded poorly to phase advances produced by morning light, whereas the "phase-advanced" half of the patients responded poorly when their rhythms delayed. However, the antidepressant responses during the best week (week of lowest depression score) were unrelated to temperature rhythm phase shifts. In general, there was not strong support for a relationship between circadian rhythms changes and antidepressant response.