Bright Light Therapy for Winter Depression—Is Phase Advancing Beneficial?

Efficacy of Morning Shorter Wavelength Lighting in the Visible (Blue) Range and Broad-Spectrum or Blue-Enriched Bright White Light in Regulating Sleep, Mood, and Fatigue in Traumatic Brain Injury: A Systematic Review

Traumatic brain injury (TBI) profoundly affects sleep, mood, and fatigue, impeding daily functioning and recovery. This systematic review evaluates the efficacy of morning shorter wavelength lighting in the visible (blue) range and broad-spectrum or blue-enriched bright white light exposure in mitigating these challenges among TBI patients. Through electronic database searches up to May 2023, studies assessing sleep, circadian rhythm, sleepiness, mood, and fatigue outcomes in TBI patients exposed to morning shorter wavelength lighting in the visible (blue) range and broad-spectrum or blue-enriched bright white light were identified. Seven studies involving 309 participants met the inclusion criteria. Results indicated consistent advancement in sleep timing among individuals with mild TBI, alongside improvements in total sleep time, mood, and reduced sleepiness with both types of light exposure, particularly in mild TBI cases. Notably, two studies demonstrated alleviation of fatigue exclusively in severe TBI cases following light exposure. Despite promising findings, evidence remains limited, emphasizing the need for future research with standardized protocols to confirm the potential and optimize the benefits of light therapy for TBI recovery.

Morning light treatment for inflammatory bowel disease: a clinical trial

BACKGROUND

Inflammatory bowel disease (IBD) affects over 3 million Americans and has a relapsing and remitting course with up to 30% of patients experiencing exacerbations each year despite the availability of immune targeted therapies. An urgent need exists to develop adjunctive treatment approaches to better manage IBD symptoms and disease activity. Circadian disruption is associated with increased disease activity and may be an important modifiable treatment target for IBD. Morning light treatment, which advances and stabilizes circadian timing, may have the potential to improve IBD symptoms and disease activity, but no studies have explored these potential therapeutic benefits in IBD. Therefore, in this study, we aim to test the effectiveness of morning light treatment for patients with IBD.

METHODS

We will recruit sixty-eight individuals with biopsy-proven IBD and clinical symptoms and randomize them to 4-weeks of morning light treatment or 4-weeks of treatment as usual (TAU), with equivalent study contact. Patient-reported outcomes (IBD-related quality of life, mood, sleep), clinician-rated disease severity, and a biomarker of gastrointestinal inflammation (fecal calprotectin) will be assessed before and after treatment. Our primary objective will be to test the effect of morning light treatment versus TAU on IBD-related quality of life and our secondary objectives will be to test the effects on clinician-rated disease activity, depression, and sleep quality. We will also explore the effect of morning light treatment versus TAU on a biomarker of gastrointestinal inflammation (fecal calprotectin), and the potential moderating effects of steroid use, restless leg syndrome, and biological sex.

DISCUSSION

Morning light treatment may be an acceptable, feasible, and effective adjunctive treatment for individuals with active IBD suffering from impaired health-related quality of life.

TRIAL REGISTRATION

The study protocol was registered on ClinicalTrials.gov as NCT06094608 on October 23, 2023, before recruitment began on February 1, 2024.

A Comprehensive Overview of the Neural Mechanisms of Light Therapy

Light is a powerful environmental factor influencing diverse brain functions. Clinical evidence supports the beneficial effect of light therapy on several diseases, including depression, cognitive dysfunction, chronic pain, and sleep disorders. However, the precise mechanisms underlying the effects of light therapy are still not well understood. In this review, we critically evaluate current clinical evidence showing the beneficial effects of light therapy on diseases. In addition, we introduce the research progress regarding the neural circuit mechanisms underlying the modulatory effects of light on brain functions, including mood, memory, pain perception, sleep, circadian rhythm, brain development, and metabolism.

Change in Seasonal Beliefs Mediates the Durability Advantage of Cognitive-Behavioral Therapy Over Light Therapy for Winter Depression

In treating an acute episode of winter depression, cognitive-behavioral therapy for seasonal affective disorder (CBT-SAD) and light therapy are comparably efficacious, with improvement in depression symptoms during CBT-SAD mediated by reduced seasonal beliefs (i.e., maladaptive thoughts about the seasons, light availability, and weather). Here, we tested whether the enduring benefit of CBT-SAD over light therapy following treatment is associated with offsetting seasonal beliefs during CBT-SAD. Currently depressed adults with Major Depression, Recurrent with Seasonal Pattern (N = 177) were randomized to 6 weeks of light therapy or group CBT-SAD and followedup one and two winters after treatment. Outcomes measured during treatment and at each follow-up included depression symptoms on the Structured Clinical Interview for the Hamilton Rating Scale for Depression-SAD Version and Beck Depression Inventory-Second Edition. Candidate mediators measured at pre-, mid-, and posttreatment were SAD-specific negative cognitions (Seasonal Beliefs Questionnaire; SBQ); general depressogenic cognitions (Dysfunctional Attitudes Scale; DAS); brooding rumination (Ruminative Response Scale-Brooding subscale; RRS-B); and chronotype (Morningness-Eveningness Questionnaire; MEQ). Latent growth curve mediation models found a significant positive path from treatment group to the slope of SBQ during treatment, with CBT-SAD showing larger improvements in seasonal beliefs with overall change in seasonal beliefs in the medium-effect range, and significant positive paths from SBQ slope to depression scores at the first and second winter follow-ups, indicating greater change towards more flexible seasonal beliefs during active treatment was associated with less severe depression symptoms following treatment. Estimated indirect effects (treatment group → SBQ change * SBQ change → outcome) were also significant at each follow-up for each outcome with βindirect ranging from .091 to .162. Models also found significant positive paths from treatment group to the slope of MEQ and RRS-B during treatment, with light therapy showing a greater increase in "morningness" and CBT-SAD showing a greater decrease in brooding during active treatment; however, neither construct emerged as a mediator of follow-up depression scores. Change in seasonal beliefs during treatment mediates both the acute antidepressant and long-term effects of CBT-SAD and explains lower depression severity following CBT-SAD relative to light therapy.

Circadian Interventions as Adjunctive Therapies to Cognitive-Behavioral Therapy for Insomnia

The circadian system plays a key role in the sleep-wake cycle. A mismatch between the behavioral timing of sleep and the circadian timing of sleepiness/alertness can contribute to insomnia. Patients who report primarily difficulty falling asleep or early morning awakenings may benefit from circadian interventions administered adjunctively to cognitive-behavioral therapy for insomnia. Specific circadian interventions that clinicians may consider include bright light therapy, scheduled dim light, blue-blocking glasses, and melatonin. Implementation of these interventions differs depending on the patient's insomnia subtype. Further, careful attention must be paid to the timing of these interventions to ensure they are administered correctly.

Sleep and circadian rhythm profiles in seasonal depression

Sleep and circadian rhythm disruptions are symptoms of, and hypothesized underlying mechanisms in, seasonal depression. Discrepant observational findings and mixed responses to sleep/circadian-based treatments suggest heterogenous sleep and circadian disruptions in seasonal depression, despite these disruptions historically conceptualized as delayed circadian phase and hypersomnia. This study used a data-driven cluster analysis to characterize sleep/circadian profiles in seasonal depression to identify treatment targets for future interventions. Biobehavioral measures of sleep and circadian rhythms were assessed during the winter in individuals with Seasonal Affective Disorder (SAD), subsyndromal-SAD (S-SAD), or nonseasonal, never depressed controls (total sample N = 103). The following variables were used in the cluster analysis: circadian phase (from dim light melatonin onset), midsleep timing, total sleep time, sleep efficiency, regularity of midsleep timing, and nap duration (all from wrist actigraphy). Sleep and circadian variables were compared across clusters and controls. Despite limited sleep/circadian differences between diagnostic groups, there were two reliable (Jaccard Coefficients >0.75) sleep/circadian profiles in SAD/S-SAD individuals: a 'Disrupted sleep' cluster, characterized by irregular and fragmented sleep and an 'Advanced' cluster, characterized by early sleep and circadian timing and longer total sleep times (>7.5 h). Clusters did not differ by depression severity. Midsleep correlated with DLMO (r = 0.56), irregularity (r = 0.3), and total sleep time (r = -0.27). Sleep and circadian disruptions in seasonal depression are not uniformly characterized by hypersomnia and circadian phase delay. Presence of distinct sleep and circadian subgroups in seasonal depression may predict successful treatment response. Prospective assessment and tailoring of individual sleep and circadian disruptions may reduce treatment failures.

Elucidating treatment targets and mediators within a confirmatory efficacy trial: study protocol for a randomized controlled trial of cognitive-behavioral therapy vs. light therapy for winter depression

BACKGROUND

This study is a confirmatory efficacy trial of two treatments for winter seasonal affective disorder (SAD): SAD-tailored group cognitive-behavioral therapy (CBT-SAD) and light therapy (LT). In our previous efficacy trial, post-treatment outcomes for CBT-SAD and LT were very similar, but CBT-SAD was associated with fewer depression recurrences two winters later than LT (27.3% in CBT-SAD vs. 45.6% in LT). CBT-SAD engaged and altered a specific mechanism of action, seasonal beliefs, which mediated CBT-SAD's acute antidepressant effects and CBT-SAD's enduring benefit over LT. Seasonal beliefs are theoretically distinct from LT's assumed target and mechanism: correction of circadian phase. This study applies the experimental therapeutics approach to determine how each treatment works when it is effective and to identify the best candidates for each. Biomarkers of LT's target and effect include circadian phase angle difference and the post-illumination pupil response. Biomarkers of CBT-SAD's target and effect include decreased pupillary and sustained frontal gamma-band EEG responses to seasonal words, which are hypothesized as biomarkers of seasonal beliefs, reflecting less engagement with seasonal stimuli following CBT-SAD. In addition to determining change mechanisms, this study tests the efficacy of a "switch" decision rule upon recurrence to inform clinical decision-making in practice.

METHODS

Adults with SAD (target N = 160) will be randomzied to 6-weeks of CBT-SAD or LT in winter 1; followed in winter 2; and, if a depression recurrence occurs, offered cross-over into the alternate treatment (i.e., switch from LT➔CBT-SAD or CBT-SAD➔LT). All subjects will be followed in winter 3. Biomarker assessments occur at pre-, mid-, and post-treatment in winter 1, at winter 2 follow-up (and again at mid-/post-treatment for those crossed-over), and at winter 3 follow-up. Primary efficacy analyses will test superiority of CBT-SAD over LT on depression recurrence status (the primary outcome). Mediation analyses will use parallel process latent growth curve modeling.

DISCUSSION

Consistent with the National Institute of Mental Health's priorities for demonstrating target engagement at the level of Research Domain Criteria-relevant biomarkers, this work aims to confirm the targets and mechanisms of LT and CBT-SAD to maximize the impact of future dissemination efforts.

TRIAL REGISTRATION

ClinicalTrials.gov identifier: NCT03691792 . Registered on October 2, 2018.

Efficacy of light therapy for a college student sample with non-seasonal subthreshold depression: An RCT study

BACKGROUND

Light therapy has been successfully used to treat seasonal and non-seasonal depression, but there is limited evidence for its efficacy in subthreshold depression. This study examines the efficacy of light therapy for symptoms of depression and anxiety in non-seasonal subthreshold depression.

METHODS

College students with non-seasonal subthreshold depression were recruited. The participants were randomly allocated to one of the three conditions: high- (LT-5000 lux) and low-intensity (LT-500 lux) light therapy conditions and a waiting-list control condition (WLC). The primary outcome was Hamilton Depression Rating Scale (HAMD), and secondary outcomes were Beck Depression Inventory-II (BDI-II) and state anxiety inventory (SAI), which were assessed at baseline (Week 0), during the trial (Week 4), and after completion of the light therapy (Week 8).

RESULTS

A total of 142 participants completed the trial. The LT-5000 (effect size [d] = 1.56, 95% CI: 1.15 to 1.98) and LT-500 conditions (d = 0.84, 95% CI: 0.43 to 1.26) were significantly superior to the WLC condition. For the LT-5000, LT-500, and WLC conditions by the end of the 8-week trial, a response on the HAMD was achieved by 70.0%, 42.0% and 19.0% of the participants, and remission was achieved by 76.0%, 54.0%, and 19.0%, respectively.

LIMITATIONS

The subjects were not followed up regularly after completion of the trial.

CONCLUSION

Light therapy, both at high- and low-intensity, was efficacious in the treatment of college students with non-seasonal subthreshold depression. High-intensity light therapy was superior to low-intensity light therapy by the end of an 8-week trial.

Detecting Critical Decision Points during Cognitive-Behavioral Therapy and Light Therapy for Winter Depression Nonremission and Recurrence

Using data from a clinical trial comparing cognitive-behavioral therapy (CBT-SAD) and light therapy (LT) for winter seasonal affective disorder (SAD; N = 177), we explored critical decision points, or treatment weeks, that predict likelihood of nonremission at post-treatment and depression recurrence following treatment. In receiver operator characteristic (ROC) curve analyses, we used weekly Structured Clinical Interview for the Hamilton Rating Scale for Depression-SAD Version (SIGH-SAD) scores during treatment to predict nonremission at post-treatment (Week 6) and recurrence one winter later (Winter 1), two winters later (Winter 2), and any recurrence. Although several C-statistics of ≥ .70 were found, only Week 4 SIGH-SAD scores in CBT-SAD for nonremission had enough predictive ability to inform clinical decision-making (C-statistic = .80; sensitivity = .91; specificity = .68). Week 4 of CBT-SAD may be a critical time point to identify likely nonremitters who need tailoring of intervention, based on SIGH-SAD cutpoint score ≥ 13. This study illustrates how clinical trial data can inform detecting optimal decision points in treatment for identifying patients unlikely to remit, a critical first step to developing adaptive treatment strategies using decision rules to operationalize when and for whom treatment should change to maximize clinical benefit.

Applying experimental therapeutics to examine cognitive and chronological vulnerabilities as mediators of acute outcomes in cognitive-behavioral therapy and light therapy for winter depression

OBJECTIVE

We applied the experimental therapeutics approach to test whether acute treatment outcomes for winter seasonal affective disorder (SAD) are mediated by a cognitive mechanism in cognitive-behavioral therapy (CBT-SAD) versus a chronobiologic mechanism in light therapy (LT).

METHOD

Currently depressed adults with major depression, recurrent with seasonal pattern (N = 177; 83.6% female, 92.1% non-Hispanic White, M age = 45.6) were randomized to 6 weeks of LT or group CBT-SAD. SAD symptoms were assessed weekly on the Structured Clinical Interview for the Hamilton Rating Scale for Depression-SAD Version. At pre-, mid-, and posttreatment, participants completed measures of general depressogenic cognitions (Dysfunctional Attitudes Scale; DAS); SAD-specific negative cognitions (Seasonal Beliefs Questionnaire; SBQ); chronotype (Morningness-Eveningness Questionnaire; MEQ); and depressive symptoms (Beck Depression Inventory-Second Edition).

RESULTS

Parallel-process growth models showed evidence for hypothesized mechanisms. For SAD-specific negative cognitions (SBQ), both symptom measures showed (1) an effect of treatment group on the slope of the mediator, with CBT-SAD demonstrating greater decreases, and (2) an effect of the slope of the mediator on the slope of the outcome. These effects held for the SBQ but not the broader measure of depressogenic cognitions (DAS). For the chronotype measure (MEQ), treatment assignment affected change, whereby LT was associated with reduced "eveningness," but this was unrelated to change in symptoms.

CONCLUSIONS

CBT-SAD promoted decreases in SAD-specific negative cognitions, and these changes were related to decreases in symptoms. Consistent with the theory that LT corrects misaligned circadian rhythms, LT reduced eveningness, but this did not correspond to symptom improvement. (PsycInfo Database Record (c) 2020 APA, all rights reserved).

Cognitive Vulnerabilities as Prognostic Predictors of Acute and Follow-up Outcomes in Seasonal Affective Disorder Treatment with Light Therapy or Cognitive-Behavioral Therapy

BACKGROUND

First-line treatments for winter seasonal affective disorder include light therapy and cognitive-behavioral therapy; however, it is unclear whether particular patient profiles respond differentially to each treatment type. This study examined baseline patient cognitive and chronobiological vulnerabilities as prognostic and prescriptive predictors of acute and follow-up treatment outcomes.

METHODS

177 adults with seasonal affective disorder were randomized to 6-weeks of either light therapy or cognitive-behavioral therapy. Participants completed baseline measures of cognitive vulnerabilities (Dysfunctional Attitudes Scale; Ruminative Response Scale; Seasonal Belief Questionnaire) and chronobiological vulnerability (Morningness-Eveningness Questionnaire). Depression was assessed at pre- and post-treatment and at follow-ups one and two winters later.

RESULTS

Pre-treatment depression severity correlated significantly with each cognitive vulnerability measure, and significantly predicted future depression. After controlling for pre-treatment depression, higher scores on the Morningness-Eveningness Questionnaire were prognostic of lower depression at treatment endpoint, but no cognitive vulnerability emerged as a prognostic or prescriptive predictor of outcome.

CONCLUSIONS

Greater morningness was associated with less severe post-treatment depression in both cognitive-behavior therapy and light therapy. No cognitive vulnerability emerged as a prognostic or prescriptive predictor, perhaps because they correlated with pre-treatment depression severity, a robust predictor of outcome. Future research should test alternative cognitive constructs.

Sleep in seasonal affective disorder

Sleep in seasonal affective disorder (SAD) has been primarily characterized by delayed sleep timing and self-reports of hypersomnolence. It is unclear whether delayed sleep timing is due to circadian or behavioral misalignment and if effective treatments operate independently of the circadian system. Discrepancies between self-report and actigraphic/polysomnographic sleep duration in SAD hinder clarification of hypersomnolence as a cardinal symptom. Previous studies have largely neglected the summer remission period in SAD, which could yield valuable insight to the role sleep disturbances play in the onset and recurrence of winter depressive episodes. Future studies should incorporate multi-method, multi-season assessment of sleep and circadian rhythms to best characterize relevant sleep-circadian phenotypes. Empirically determining sleep phenotypes present in SAD will pave the way for targeted sleep interventions.

An Open Trial of Morning Bright Light Treatment Among US Military Veterans with Chronic Low Back Pain: A Pilot Study

OBJECTIVE

To examine the feasibility, acceptability, and effects of a home-based morning bright light treatment on pain, mood, sleep, and circadian timing in US veterans with chronic low back pain.

DESIGN

An open treatment trial with a seven-day baseline, followed by 13 days of a one-hour morning bright light treatment self-administered at home. Pain, pain sensitivity, mood, sleep, and circadian timing were assessed before, during, and after treatment.

SETTING

Participants slept at home, with weekly study visits and home saliva collections.

PARTICIPANTS

Thirty-seven US veterans with medically verified chronic low back pain.

METHODS

Pain, mood, and sleep quality were assessed with questionnaires. Pain sensitivity was assessed using two laboratory tasks: a heat stimulus and an ischemia stimulus that gave measures of threshold and tolerance. Sleep was objectively assessed with wrist actigraphy. Circadian timing was assessed with the dim light melatonin onset.

RESULTS

Morning bright light treatment led to reduced pain intensity, pain behavior, thermal pain threshold sensitivity, post-traumatic stress disorder symptoms, and improved sleep quality (P < 0.05). Phase advances in circadian timing were associated with reductions in pain interference (r = 0.55, P < 0.05).

CONCLUSIONS

Morning bright light treatment is a feasible and acceptable treatment for US veterans with chronic low back pain. Those who undergo morning bright light treatment may show improvements in pain, pain sensitivity, and sleep. Advances in circadian timing may be one mechanism by which morning bright light reduces pain. Morning bright light treatment should be further explored as an innovative treatment for chronic pain conditions.

Circadian regulation of depression: A role for serotonin

Synchronizing circadian (24 h) rhythms in physiology and behavior with the environmental light-dark cycle is critical for maintaining optimal health. Dysregulation of the circadian system increases susceptibility to numerous pathological conditions including major depressive disorder. Stress is a common etiological factor in the development of depression and the circadian system is highly interconnected to stress-sensitive neurotransmitter systems such as the serotonin (5-hydroxytryptamine, 5-HT) system. Thus, here we propose that stress-induced perturbation of the 5-HT system disrupts circadian processes and increases susceptibility to depression. In this review, we first provide an overview of the basic components of the circadian system. Next, we discuss evidence that circadian dysfunction is associated with changes in mood in humans and rodent models. Finally, we provide evidence that 5-HT is a critical factor linking dysregulation of the circadian system and mood. Determining how these two systems interact may provide novel therapeutic targets for 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.

Light rescues circadian behavior and brain dopamine abnormalities in diurnal rodents exposed to a winter-like photoperiod

Seasonal affective disorder (SAD), beyond mood changes, is characterized by alterations in daily rhythms of behavior and physiology. The pathophysiological conditions of SAD involve changes in day length and its first-line treatment is bright light therapy. Animal models using nocturnal rodents have been studied to elucidate the neurobiological mechanisms of depression, but might be ill suited to study the therapeutic effects of light in SAD since they exhibit light-aversive responses. Here Arvicanthis ansorgei, a diurnal rodent, was used to determine behavioral, molecular and brain dopamine changes in response to exposure to a winter-like photoperiod consisting of a light-dark cycle with 8 h of light, under diminished light intensity, and 16 h of darkness. Furthermore, we evaluated whether timed-daily bright light exposure has an effect on behavior and brain physiology of winter-like exposed animals. Arvicanthis under a winter-like condition showed alterations in the synchronization of the locomotor activity rhythm to the light-dark cycle. Moreover, alterations in day-night activity of dopaminergic neurotransmission were revealed in the nucleus accumbens and the dorsal striatum, and in the day-night clock gene expression in the suprachiasmatic nucleus. Interestingly, whereas dopamine disturbances were reversed in animals exposed to daily light at early or late day, altered phase of the daily rhythm of locomotion was reverted only in animals exposed to light at the late day. Moreover, Per2 gene expression in the SCN was also affected by light exposure at late day in winter-like exposed animals. These findings suggest that light induces effects on behavior by mechanisms that rely on both circadian and rhythm-independent pathways influencing the dopaminergic circuitry. This last point might be crucial for understanding the mechanisms of non-pharmacological treatment in SAD.

Bright light and oxygen therapies decrease delirium risk in critically ill surgical patients by targeting sleep and acid-base disturbances

This study examined the effects of bright light therapy (BLT) on the incidence of delirium in post-operative patients admitted to a surgical intensive care unit (SICU) and delineates risk and protective factors. We included 62 patients in a single-blind, randomized controlled study. The intervention group was treated with care as usual plus BLT for three consecutive days. Delirium was diagnosed by DSM-5 criteria with the Confusion Assessment Method-Intensive Care Unit (CAM-ICU). Risk factors for delirium were measured, including the APACHE II score, Insomnia Severity Index (ISI), as well as hematocrit and bicarbonate levels. Results were adjusted for treatment with nasal cannula oxygen and medications. Thirteen patients developed delirium within the three days following surgery. Generalized estimating equations analysis showed a significant preventive effect of BLT on delirium, which was independent of risk or treatment factors. Higher APACHE-II and ISI scores, lower hematocrit and lower bicarbonate levels increased the risk of developing delirium. BLT plus nasal cannula oxygen significantly reduced the likelihood of delirium. BLT significantly lowered ISI scores, while nasal cannula oxygen significantly enhanced bicarbonate levels. The results indicate that BLT and supplementary oxygen therapy may protect against delirium by targeting sleep-wake and deficits in the bicarbonate buffer system.

Correcting delayed circadian phase with bright light therapy predicts improvement in ADHD symptoms: A pilot study

Attention-deficit/hyperactivity disorder (ADHD) is a common condition with comorbid insomnia reported in >70% of children and adults. These patients demonstrate delays in sleep-wake rhythms, nocturnal rise in melatonin, and early morning rise in cortisol. Given that standard psychopharmacologic treatments for ADHD often do not completely control symptoms in participants with circadian rhythm delay, we sought to test whether bright light therapy (BLT) advances circadian rhythms and further reduces ADHD symptoms over standard treatments. In addition to standard of care, participants with ADHD diagnosis underwent 1 week of baseline assessment followed by 2-weeks of 30-min morning 10,000-lux BLT beginning 3 h after mid-sleep time. Participants minimized overhead light after 4 p.m., wore an actigraphy watch, and recorded BLT time on daily sleep logs. Dim Light Melatonin Onset (DLMO) was assessed at baseline and after 2-week treatment. ADHD symptoms were measured by the ADHD-Rating Scales (ADHD-RS). BLT significantly advanced the phase of DLMO by 31 min [mean time (SEM), 20:36 (0:21) advanced to 20:05 (0:20)] and mid-sleep time by 57 min [4:37 (0:22) advanced to 3:40 (0:16); paired t-tests, p = 0.002 and 0.004, respectively). Phase advances (in DLMO or mid-sleep time) were significantly correlated with decreased ADHD-RS total scores (p = 0.027 and 0.044) and Hyperactive-Impulsive sub-scores (p = 0.014 and 0.013, respectively). Actigraphy analysis for a subset of 8 participants with significant DLMO phase advance revealed no significant changes in total sleep time, sleep efficiency, wake after sleep onset, or percent wake during sleep interval. This is the first successful use of BLT for advancing melatonin phase and improving ADHD symptoms in adults. BLT may be a complementary treatment for both delayed sleep timing and ADHD symptoms in adults.

Effect of Light and Melatonin and Other Melatonin Receptor Agonists on Human Circadian Physiology

Circadian (body clock) timing has a profound influence on mental health, physical health, and health behaviors. This review focuses on how light, melatonin, and other melatonin receptor agonist drugs can be used to shift circadian timing in patients with misaligned circadian rhythms. A brief overview of the human circadian system is provided, followed by a discussion of patient characteristics and safety considerations that can influence the treatment of choice. The important features of light treatment, light avoidance, exogenous melatonin, and other melatonin receptor agonists are reviewed, along with some of the practical aspects of light and melatonin treatment.

Cognitive-behavioral therapy vs. light therapy for preventing winter depression recurrence: study protocol for a randomized controlled trial

BACKGROUND

Seasonal affective disorder (SAD) is a subtype of recurrent depression involving major depressive episodes during the fall and/or winter months that remit in the spring. The central public health challenge in the management of SAD is prevention of winter depression recurrence. Light therapy (LT) is the established and best available acute SAD treatment. However, long-term compliance with daily LT from first symptom through spontaneous springtime remission every fall/winter season is poor. Time-limited alternative treatments with effects that endure beyond the cessation of acute treatment are needed to prevent the annual recurrence of SAD.

METHODS/DESIGN

This is an NIMH-funded R01-level randomized clinical trial to test the efficacy of a novel, SAD-tailored cognitive-behavioral group therapy (CBT) against LT in a head-to-head comparison on next winter outcomes. This project is designed to test for a clinically meaningful difference between CBT and LT on depression recurrence in the next winter (the primary outcome). This is a concurrent two-arm study that will randomize 160 currently symptomatic community adults with major depression, recurrent with seasonal pattern, to CBT or LT. After 6 weeks of treatment in the initial winter, participants are followed in the subsequent summer, the next winter, and two winters later. Key methodological issues surround timing study procedures for a predictably recurrent and time-limited disorder with a focus on long-term outcomes.

DISCUSSION

The chosen design answers the primary question of whether prior exposure to CBT is associated with a substantially lower likelihood of depression recurrence the next winter than LT. This design does not test the relative contributions of the cognitive-behavioral treatment components vs. nonspecific factors to CBT's outcomes and is not adequately powered to test for differences or equivalence between cells at treatment endpoint. Alternative designs addressing these limitations would have required more patients, increased costs, and reduced power to detect a difference in the primary outcome.

TRIAL REGISTRATION

Clinicaltrials.gov identifier NCT01714050.

Improvement in depression scores after 1 hour of light therapy treatment in patients with seasonal affective disorder

The purpose of this study was to investigate possible rapid effects of light therapy on depressed mood in patients with seasonal affective disorder. Participants received 1 hour of bright light therapy and 1 hour of placebo dim red light in a randomized order crossover design. Depressed mood was measured at baseline and after each hour of light treatment using two self-report depression scales (Profile of Mood States-Depression-Dejection [POMS-D] subscale and the Beck Depression Inventory II [BDI-II]). When light effects were grouped for the two sessions, there was significantly greater reduction in self-report depression scores by -1.3 (p = 0.02) on the BDI-II and -1.2 (p = 0.02) on the POMS-D. A significant but modest improvement was detected after a single active light session. This is the first study, to our knowledge, to document an immediate improvement with light treatment using a placebo-controlled design with a clinical sample of depressed individuals.

Relationship of morningness-eveningness questionnaire score to melatonin and sleep timing, body mass index and atypical depressive symptoms in peri- and post-menopausal women

Previous work shows a relationship between measures of morning or evening preference (e.g., morningness-eveningness questionnaire (MEQ) scores) and melatonin and sleep timing, body mass index (BMI) and mood. This study explores the relationship of these factors to atypical depression (ATD) symptoms, particularly increased appetite and hypersomnia, in depressed and non-depressed peri- and post-menopausal women. Participants were 19 normal control subjects and 10 depressed patients, 46-72 years of age. In a university hospital setting, we administered the MEQ and Structured Interview Guide for the Hamilton Depression Rating Scale, Seasonal Affective Disorders (SIGH-SAD version), which includes a measure of ATD, 3-5 weeks before obtaining nighttime polysomnography and overnight plasma melatonin in dim light (<30lx). Scores on SIGH-SAD appetite-related items were significantly correlated with MEQ, dim light melatonin onset (DLMO) time and midsleep time (MST); BMI was related to MST, sleep end time, phase-angle differences between sleep and melatonin timing, and appetite measures. Results suggest that relative to women with earlier DLMOs and MSTs, depressed peri- and post-menopausal women whose DLMOs and MSTs are phase-delayed may experience increases in appetite, hypersomnia, and BMI. These symptoms might be relieved by sleep or light manipulations that advance melatonin and sleep timing parameters.

Less Exposure to Daily Ambient Light in Winter Increases Sensitivity of Melatonin to Light Suppression

This study was carried out to examine the seasonal difference in the magnitude of the suppression of melatonin secretion induced by exposure to light in the late evening. The study was carried out in Akita (39 degrees North, 140 degrees East), in the northern part of Japan, where the duration of sunshine in winter is the shortest. Ten healthy male university students (mean age: 21.9+/-1.2 yrs) volunteered to participate twice in the study in winter (from January to February) and summer (from June to July) 2004. According to Japanese meteorological data, the duration of sunshine in Akita in the winter (50.5 h/month) is approximately one-third of that in summer (159.7 h/month). Beginning one week prior to the start of the experiment, the level of daily ambient light to which each subject was exposed was recorded every minute using a small light sensor that was attached to the subject's wrist. In the first experiment, saliva samples were collected every hour over a period of 24 h in a dark experimental room (<15 lux) to determine peak salivary melatonin concentration. The second experiment was conducted after the first experiment to determine the percentage of melatonin suppression induced by exposure to light. The starting time of exposure to light was set 2 h before the time of peak salivary melatonin concentration detected in the first experiment. The subjects were exposed to light (1000 lux) for 2 h using white fluorescent lamps (4200 K). The percentage of suppression of melatonin by light was calculated on the basis of the melatonin concentration determined before the start of exposure to light. The percentage of suppression of melatonin 2 h after the start of exposure to light was significantly greater in winter (66.6+/-18.4%) than summer (37.2+/-33.2%), p<0.01). The integrated level of daily ambient light from rising time to bedtime in summer was approximately twice that in winter. The results suggest that the increase in suppression of melatonin by light in winter is caused by less exposure to daily ambient light.

Effect of antidepressants on melatonin metabolite in depressed patients

Antidepressants increase melatonin levels, but it is still unclear whether this effect is related to the improvement of depressive symptoms or to unrelated pharmacological action of antidepressants. To answer this question, the effect of antidepressants on 6-sulphatoxymelatonin (aMT6s), the main melatonin urinary metabolite, was examined in drug-free depressed patients - most of them antidepressant-naive. aMT6s was evaluated in 34 depressed patients, before and after 8 weeks of placebo (n = 12) or antidepressant (n = 22; fluoxetine, duloxetine or Hypericum perforatum). Both groups showed an improvement of depressive symptoms after treatment compared to baseline (Hamilton Depression scores): 17.0 +/- 1.4 vs. 9.0 +/- 2.8, P = 0.007 for placebo, and 18.6 +/- 1.1 vs. 11.8 +/- 1.6, P < 0.001 for antidepressants). After treatment, aMT6s levels increased after antidepressants (P < 0.01), but not after placebo (P > 0.05). As depressive symptoms improved both in patients taking antidepressant and in those taking placebo, but an effect of antidepressants could only be seen in those taking antidepressants, we suggest that melatonin changes after antidepressants are more likely due to a pharmacological action of these drugs on melatonin secretion.

The chronobiology and neurobiology of winter seasonal affective disorder

This review summarizes research on the chronobiology and neurobiology of winter seasonal affective disorder (SAD), a recurrent subtype of depression characterized by a predictable onset in the fall/winter months and spontaneous remission in the spring/summer period. Chronobiological mechanisms related to circadian rhythms, melatonin, and photoperiodism play a significant role in many cases of SAD, and treatment of SAD can be optimized by considering individual differences in key chronobiological markers. Converging evidence also points to a role for the major monoamine neurotransmitters serotonin, norepinephrine, and dopamine in one or more aspects of SAD. Ultimately, as with other psychiatric illnesses, SAD is best considered as a complex disorder resulting from the interaction of several vulnerability factors acting at different levels, the various genetic mechanisms that underlie them, and the physical environment. Models of SAD that emphasize its potential role in human evolution will also be discussed.

Circadian genes, rhythms and the biology of mood disorders

For many years, researchers have suggested that abnormalities in circadian rhythms may underlie the development of mood disorders such as bipolar disorder (BPD), major depression and seasonal affective disorder (SAD). Furthermore, some of the treatments that are currently employed to treat mood disorders are thought to act by shifting or "resetting" the circadian clock, including total sleep deprivation (TSD) and bright light therapy. There is also reason to suspect that many of the mood stabilizers and antidepressants used to treat these disorders may derive at least some of their therapeutic efficacy by affecting the circadian clock. Recent genetic, molecular and behavioral studies implicate individual genes that make up the clock in mood regulation. As well, important functions of these genes in brain regions and neurotransmitter systems associated with mood regulation are becoming apparent. In this review, the evidence linking circadian rhythms and mood disorders, and what is known about the underlying biology of this association, is presented.

Alterations in circadian rhythm phase shifting ability in rats following ethanol exposure during the third trimester brain growth spurt

BACKGROUND

Disruptions in sleep and feeding rhythms are among the consequences of prenatal alcohol exposure. Previously, we reported that ethanol exposure during the second trimester equivalent in rats produces long-lasting impairments in circadian system functioning. In the present study, we examined the effects of ethanol exposure during the third trimester equivalent brain growth spurt on the development of the circadian clock system.

METHODS

Sprague-Dawley male rat pups were exposed to 6.0 g/kg/d ethanol via an artificial rearing procedure on postnatal days (PD) 4 through 9 (EtOH). An artificially reared gastrostomized control group and a normally reared suckle control group were also included. At 10 to 12 weeks of age, wheel-running behavior was measured continuously under a 12-hour/12-hour light/dark (LD) cycle. Thereafter, subjects were exposed to a 6-hour phase delay of the LD cycle, and the ability to adjust to the new LD cycle was evaluated.

RESULTS

Before the phase delay, onset time of activity and acrophases of activity in all 3 groups were not significantly different from one another. After the 6-hour LD cycle delay, EtOH subjects were slower to adapt to the new cycle compared with both control groups, as measured by both activity onset and acrophase. Throughout the experiment, activity levels of EtOH subjects tended to be higher compared to both controls.

CONCLUSIONS

These data demonstrate that ethanol exposure during the third trimester disrupts the ability to synchronize circadian rhythm to light cues. Disruptions in circadian regulation may cause abnormal behavioral rhythmicity, such as disrupted sleep and feeding patterns, as seen in individuals prenatally exposed to ethanol.

The circadian basis of winter depression

The following test of the circadian phase-shift hypothesis for patients with winter depression (seasonal affective disorder, or SAD) uses low-dose melatonin administration in the morning or afternoon/evening to induce phase delays or phase advances, respectively, without causing sleepiness. Correlations between depression ratings and circadian phase revealed a therapeutic window for optimal alignment of circadian rhythms that also appears to be useful for phase-typing SAD patients for the purpose of administering treatment at the correct time. These analyses also provide estimates of the circadian component of SAD that may apply to the antidepressant mechanism of action of appropriately timed bright light exposure, the treatment of choice. SAD may be the first psychiatric disorder in which a physiological marker correlates with symptom severity before, and in the course of, treatment in the same patients. The findings support the phase-shift hypothesis for SAD, as well as suggest a way to assess the circadian component of other psychiatric, sleep, and chronobiologic disorders.

Multi-target strategies for the improved treatment of depressive states: Conceptual foundations and neuronal substrates, drug discovery and therapeutic application

Major depression is a debilitating and recurrent disorder with a substantial lifetime risk and a high social cost. Depressed patients generally display co-morbid symptoms, and depression frequently accompanies other serious disorders. Currently available drugs display limited efficacy and a pronounced delay to onset of action, and all provoke distressing side effects. Cloning of the human genome has fuelled expectations that symptomatic treatment may soon become more rapid and effective, and that depressive states may ultimately be "prevented" or "cured". In pursuing these objectives, in particular for genome-derived, non-monoaminergic targets, "specificity" of drug actions is often emphasized. That is, priority is afforded to agents that interact exclusively with a single site hypothesized as critically involved in the pathogenesis and/or control of depression. Certain highly selective drugs may prove effective, and they remain indispensable in the experimental (and clinical) evaluation of the significance of novel mechanisms. However, by analogy to other multifactorial disorders, "multi-target" agents may be better adapted to the improved treatment of depressive states. Support for this contention is garnered from a broad palette of observations, ranging from mechanisms of action of adjunctive drug combinations and electroconvulsive therapy to "network theory" analysis of the etiology and management of depressive states. The review also outlines opportunities to be exploited, and challenges to be addressed, in the discovery and characterization of drugs recognizing multiple targets. Finally, a diversity of multi-target strategies is proposed for the more efficacious and rapid control of core and co-morbid symptoms of depression, together with improved tolerance relative to currently available agents.

O sweet spot where art thou? Light treatment of Seasonal Affective Disorder and the circadian time of sleep

This study investigated Lewy's Phase Shift Hypothesis (PSH) for winter Seasonal Affective Disorder, which asserts that the phase angle difference (PAD) between circadian and sleep rhythms is critical in the mechanism of light's therapeutic action. Specifically, we sought to test whether a euthymic "sweet spot" could be identified at a PAD (between temperature minimum and wake time) of circa 3 h. After a baseline week, symptomatic SAD patients (N = 43) received 8 weeks of morning light treatment. Analyses were based on SIGH-SAD ratings made at baseline and posttreatment. Also estimated pre- and posttreatment were T(min) (calculated from an algorithm based on Morningness-Eveningness self-report scores), and the phase of the sleep-wake rhythm (as assessed by daily sleep logs). It was predicted that a quadratic relationship would exist between PAD and depression ratings at baseline and posttreatment, with lowest levels around PAD = 3 h. It was further predicted that shift towards PAD = 3 h with treatment would be associated with decreases in depression with treatment. Although trends were in the expected direction, none of the three predictions were supported. Findings are discussed in terms of the study's limitations and the experimental challenge of parsing independent and interacting contributions of sleep and circadian phase.

The selective tachykinin neurokinin 1 (NK1) receptor antagonist, GR 205,171, stereospecifically inhibits light-induced phase advances of hamster circadian activity rhythms

Circadian rhythms in mammals are generated by master pacemaker cells located within the suprachiasmatic nucleus of the hypothalamus. In hamsters, the suprachiasmatic nucleus contains a small collection of cells immunoreactive for substance P, the endogenous ligand of tachykinin neurokinin 1 (NK1) receptors. In addition, two other nuclei which form part of the circadian system, the intergeniculate leaflet of the thalamus and the raphe nuclei, also contain fibers and/or cell bodies immunoreactive for substance P. In light of these observations, we evaluated the influence of the selective tachykinin NK1 receptor antagonist, GR 205,171, upon circadian activity rhythms in the hamster. Systemic injection of GR 205,171 dose-dependently (2.5-40.0 mg/kg, i.p.) inhibited light-induced phase advances in hamster circadian wheel running activity rhythms by approximately 50%. In contrast, GR 226,206, the less active enantiomer of GR 205,171, failed to affect light-induced phase advances. In addition, we examined the potential ability of GR 205,171 to induce non-photic phase shifts in hamster wheel running rhythms when injected at mid-day to late night circadian times. However, GR 205,171 (40 mg/kg) did not elicit non-photic phase shifts at these times indicating that tachykinin NK1 receptor antagonists are only effective when a light stimulus is applied to the pacemaker. Although GR 205,171 may, in theory, activate several sites within the circadian system, we suggest that GR 205,171 acts in the raphe nuclei to increase inhibitory serotonergic input to pacemaker cells in the suprachiasmatic nuclei, thereby suppressing photic modulation of the pacemaker. These findings have important implications for the use of tachykinin NK1 receptor antagonists in the treatment of depression and other central nervous system disorders.

Update on the biology of seasonal affective disorder

The etiology and pathophysiology of seasonal affective disorder (SAD) has been linked to the seasons and to light since its first conceptualization. Aspects of SAD that make it particularly amenable to biological investigation include the predictable recurrent episodes, the rapid response to a nonpharmacologic treatment, the specific neurovegetative features, and the availability of rich animal models of seasonality. This paper reviews new findings for the major biological hypotheses for SAD, focusing on circadian rhythms, neurotransmitters, and molecular genetics. Integrative issues and future directions for the study of SAD, including the heuristic value of a dual-vulnerability hypothesis that conceptualizes seasonality as a dimensional construct and the importance of studying endophenotypes, will be discussed.