Morning Bright Light Research Articles

Early morning bright light therapy: its next-day effects on early morning physical performance, temperature, and mood

Many different popular sports such as swimming, rowing or team-based sports involve having to perform whether in training or competition at a high level in the early morning (Olympics.com, 2023). Various research papers in the past have shown that there is a distinct diurnal variation in physical performance. Finding ways to improve early morning performance would greatly benefit many athletes and teams in multiple disciplines. 11 active males [mean ± SD: age, 21 ± 1 years, body mass, 78 ± 8 kg and stature, 180 ± 5 cm) volunteered, completed two familiarisations. Then two experimental sessions randomly allocated in a counterbalanced order 1) bright light therapy/ 2) no bright light therapy was administered at 07:00 h for 1 h the next morning (07:00 h) participants came into the laboratory where Intra-aural temperature, mood was assessed using the Perceived Onset Mood State questionnaire and right and left grip strength using a hand grip dynamometer were taken. Finally, participants undertook a warmup, the completed 10 × 20 m repeated sprints (RS) with 30 s recoveries on an indoor running track, with heart rate, finishing time and perceived exertion measured every sprint. Blood lactate was measured at rest, after the warm-up and post RS. Data were analysed using general-linear models.

Feasibility and acceptability for LION, a fully remote, randomized clinical trial within the VA for light therapy to improve sleep in Veterans with and without TBI: An MTBI2 sponsored protocol.

Sleep-wake disturbances frequently present in Veterans with mild traumatic brain injury (mTBI). These TBI-related sleep impairments confer significant burden and commonly exacerbate other functional impairments. Therapies to improve sleep following mTBI are limited and studies in Veterans are even more scarce. In our previous pilot work, morning bright light therapy (MBLT) was found to be a feasible behavioral sleep intervention in Veterans with a history of mTBI; however, this was single-arm, open-label, and non-randomized, and therefore was not intended to establish efficacy. The present study, LION (light vs ion therapy) extends this preliminary work as a fully powered, sham-controlled, participant-masked randomized controlled trial (NCT03968874), implemented as fully remote within the VA (target n=120 complete). Randomization at 2:1 allocation ratio to: 1) active: MBLT (n=80), and 2) sham: deactivated negative ion generator (n=40); each with identical engagement parameters (60-min duration; within 2-hrs of waking; daily over 28-day duration). Participant masking via deception balanced expectancy assumptions across arms. Outcome measures were assessed following a 14-day baseline (pre-intervention), following 28-days of device engagement (post-intervention), and 28-days after the post-intervention assessment (follow-up). Primary outcomes were sleep measures, including continuous wrist-based actigraphy, self-report, and daily sleep dairy entries. Secondary/exploratory outcomes included cognition, mood, quality of life, circadian rhythm via dim light melatonin onset, and biofluid-based biomarkers. Participant drop out occurred in <10% of those enrolled, incomplete/missing data was present in <15% of key outcome variables, and overall fidelity adherence to the intervention was >85%, collectively establishing feasibility and acceptability for MBLT in Veterans with mTBI.

Bright Light Therapy as Add-On to Inpatient Treatment in Youth With Moderate to Severe Depression

Major depressive disorder is one of the most common mental disorders among adolescents, entailing severe, long-term psychosocial impairment and a high risk of chronicity. In view of the large number of patients requiring treatment, along with insufficient treatment responses with small effect sizes, innovative adjunctive treatment strategies are urgently needed. To investigate whether the effect of adolescent psychiatric inpatient treatment as usual for major depressive disorder can be enhanced by simultaneous use of morning bright light therapy. This was a double-blind, placebo-controlled randomized parallel-group trial with enrollment between March 2018 and November 2020 and follow-up completed in May 2021. The study took place among inpatients at 4 university hospitals for child and adolescent psychiatry across Germany. Of 248 eligible youth aged 12 to 18 years fulfilling ICD-10 criteria for major depressive disorder, 227 were randomized to bright light therapy (n = 116) or placebo red light (n = 111); 151 participants completed the study. Up to 20 sessions of either morning bright light therapy with an intensity of 10 000 lux or placebo red light (100 lux) in addition to multimodal inpatient treatment as usual over 4 weeks. The primary outcome was the change in Beck Depression Inventory-II (BDI-II) score from baseline to posttreatment in the intention-to-treat sample. Among the 224 patients included in the intention-to-treat analyses (192 girls and 32 boys; mean [SD] age, 15.5 [1.4] years), the mean (SD) BDI-II score at baseline was 37.3 (8.7). BDI-II scores were significantly reduced after 4 weeks (postassessment) by a mean of -7.5 (95% CI, -9.0 to -6.0; Hedges g = 0.71). Bright light therapy had no impact on this change (no significant group × time effect). Loss to follow-up was 31% (n = 69) at 16 weeks and 49% (n = 110) at 28 weeks. There were 10 serious adverse events throughout the whole trial, which were not considered related to study treatment. The findings in this study did not indicate superiority of bright light therapy over placebo red light therapy in a large sample of adolescent inpatients with moderate or severe major depressive disorder. Both groups benefited equally from treatment as usual, showing relevant symptom reduction. German Clinical Trials Register: DRKS00013188.

Greater sensitivity of the circadian system of women to bright light, but not dim-to-moderate light.

Women typically sleep and wake earlier than men and have been shown to have earlier circadian timing relative to the light/dark cycle that synchronizes the clock. A potential mechanism for earlier timing in women is an altered response of the circadian system to evening light. We characterized individual-level dose-response curves for light-induced melatonin suppression using a within-subjects protocol. Fifty-six participants (29 women, 27 men; aged 18-30 years) were exposed to a range of light illuminances (10, 30, 50, 100, 200, 400, and 2000 lux) using melatonin suppression relative to a dim control (<1 lux) as a marker of light sensitivity. Women were free from hormonal contraception. To examine the potential influence of sex hormones, estradiol and progesterone was examined in women and testosterone was examined in a subset of men. Menstrual phase was monitored using self-reports and estradiol and progesterone levels. Women exhibited significantly greater melatonin suppression than men under the 400-lux and 2000-lux conditions, but not under lower light conditions (10-200 lux). Light sensitivity did not differ by menstrual phase, nor was it associated with levels of estradiol, progesterone, or testosterone, suggesting the sex differences in light sensitivity were not acutely driven by circulating levels of sex hormones. These results suggest that sex differences in circadian timing are not due to differences in the response to dim/moderate light exposures typically experienced in the evening. The finding of increased bright light sensitivity in women suggests that sex differences in circadian timing could plausibly instead be driven by a greater sensitivity to phase-advancing effects of bright morning light.

Extending weeknight sleep duration in late-sleeping adolescents using morning bright light on weekends: a 3-week maintenance study.

Our sleep extension intervention in adolescents showed that gradually shifting weekday bedtime earlier plus one weekend of morning bright light advanced circadian phase and increased weeknight sleep duration. Here, we examine at-home maintenance of these changes. Fourteen adolescents (15.3-17.9 years; 7 female) completed a 7-week study. After usual sleep at home (2-week baseline), intervention participants (n = 8) gradually advanced weekday bedtime (1 hour earlier than baseline during week 3; 2 hours earlier in week 4) and received bright light (~6000 lux; 2.5 hours) on both mornings of the intervening weekend. During three maintenance weeks, intervention participants were instructed to maintain their school-day wake-up time on all days, keep their early week four bedtimes, except on weekends when they could go to bed up to 1 hour later, and get a 2.5-hour light box exposure within 5 minutes of waking on one morning (Saturday orSunday) of both weekends at home. Control participants (n = 6) slept as usual at home and did not receive weekend bright light. Dim light melatonin onset (DLMO) was measured after the 2-week baseline, 2-week intervention, and 3-week maintenance in all participants. Actigraphic sleep-wake was collected throughout. After the 2-week intervention, DLMOs advanced more compared to control (37.0 ± 40.0 minutes vs. -14.7 ± 16.6 minutes), weekday sleep duration increased by 69.7 ± 27.8 minutes and sleep onset was 103.7 ± 14.2 minutes earlier compared to baseline. After three maintenance weeks, intervention participants showed negligible DLMO delays (-4.9 ± 22.9 minutes); weekday fall-asleep times and sleep durations also remained stable. Early circadian phase and extended sleep can be maintained with at-home weekend bright light.

Responses to bright light exposure in individuals with binge-spectrum eating disorders characterized by high dietary restraint and negative affect.

Circadian rhythm disruptions are associated with binge eating, can be causal of negative mood, and may be corrected with bright light exposure. A subtype of individuals with binge-spectrum eating disorders are characterized by combined high dietary restraint and negative affect. These individuals have higher eating disorder psychopathology and poorer treatment response. We aimed to test the targeted effects of morning bright light exposure on individuals with binge-spectrum eating disorders, hypothesizing significant reductions in binge eating for those characterized by high dietary restraint and negative affect. Participants (N = 34 females with binge-eating disorder and bulimia nervosa) used a morning bright light and normal light for 10 consecutive days each, in randomized order. They completed the Change in Eating Disorder Symptoms (CHEDS) scaleat baseline, day 12 (when they switched lamps), and day 22. We conducted moderation analyses, clustering data by person, controlling for order, and examining the effect of light condition on binge eating according to baseline restraint and negative affect. At high levels of combined dietary restraint and negative affect, participants experienced a reduction in binge eating and food preoccupation following exposure to morning bright light. There were no changes in restrictive eating, body preoccupation, body dissatisfaction, or body checking following exposure to morning bright light for these individuals. These findings suggest that morning bright light may be a useful adjunct to empirically supported eating disorder treatments that target binge eating, especially for individuals characterized by the difficult to treat restraint/negative affect subtype. At high levels of combined dietary restraint and negative affect, participants with binge-spectrum eating disorders experienced a reduction in binge eating and food preoccupation following exposure to morning bright light. These findings suggest that morning bright light may be a useful adjunct to empirically supported eating disorder treatments that target binge eating, especially for individuals characterized by the difficult-to-treat restraint/negative affect subtype.

Bright light therapy and early morning attention, mathematical performance, electroencephalography and brain connectivity in adolescents with morning sleepiness.

Adolescents typically sleep too little and feel drowsy during morning classes. We assessed whether morning use of an LED bright light device could increase alertness in school students. Twenty-six (8M/18F) healthy, unmedicated participants, ages 13-18 years, (mean 17.1±1.4) were recruited following screenings to exclude psychopathology. Baseline assessments were made of actigraph-assessed sleep, attention, math solving ability, electroencephalography and structural and functional MRI (N = 10-11, pre-post). Participants nonrandomly received 3-4 weeks of bright light therapy (BLT) for 30 minutes each morning and used blue light blocking glasses for 2 hours before bedtime. BLT devices were modified to surreptitiously record degree of use so that the hypothesis tested was whether there was a significant relationship between degree of use and outcome. They were used 57±18% (range 23%-90%) of recommended time. There was a significant association between degree of use and: (1) increased beta spectral power in frontal EEG leads (primary measure); (2) greater post-test improvement in math performance and reduction in errors of omission on attention test; (3) reduced day-to-day variability in bed times, sleep onset, and sleep duration during school days; (4) increased dentate gyrus volume and (5) enhanced frontal connectivity with temporal, occipital and cerebellar regions during Go/No-Go task performance. BLT was associated with improvement in sleep cycle consistency, arousal, attention and functional connectivity, but not sleep onset or duration (primary measures). Although this was an open study, it suggests that use of bright morning light and blue light blocking glasses before bed may benefit adolescents experiencing daytime sleepiness. Clinical trial registration: Clinicaltrials.gov ID-NCT05383690.

Circadian aspects in the aetiology and pathophysiology of insomnia.

Because the endogenous circadian pacemaker is a very strong determinant of alertness/sleep propensity across the 24 h period, its mistiming may contribute to symptoms of insomnia (e.g., difficulties initiating sleep and maintaining sleep) and to the development of insomnia disorder. Despite the separation of insomnia and circadian rhythm disorders in diagnostic nosology implying independent pathophysiology, there is considerable evidence of co-morbidity and interaction between them. Sleep onset insomnia is associated with later timed circadian rhythms and can be treated with morning bright light to shift rhythms to an earlier timing. It is also possible that the causal link may go in both directions and that having a delayed circadian rhythm can result in enough experiences of delayed sleep onset to lead to some conditioned insomnia or insomnia disorder further exacerbating a delayed circadian rhythm. Early morning awakening insomnia is associated with an advanced circadian phase (early timing) and can be treated with evening bright light resulting in a delay of rhythms and an improved ability to sleep later in the morning and to obtain more sleep. There is some evidence suggesting that sleep maintenance insomnia is associated with a blunted amplitude of circadian rhythm that may be treated with increased regularity of sleep and light exposure timing. However, this is an insomnia phenotype that requires considerably more circadian research as well as further insomnia clinical research with the other insomnia phenotypes incorporating circadian timing measures and treatments.

Sleep-light interventions that shift melatonin rhythms earlier improve perimenopausal and postmenopausal depression: preliminary findings.

Testing the hypothesis that a sleep-light intervention, which phase-advances melatonin rhythms, will improve perimenopausal-postmenopausal (P-M; by follicle-stimulating hormone) depression. In at-home environments, we compared two contrasting interventions: (1) an active phase-advance intervention: one night of advanced/restricted sleep from 9 pm to 1 am , followed by 8 weeks of morning bright white light for 60 min/d within 30 minutes of awakening, and (2) a control phase-delay intervention: one night of delayed/restricted sleep (sleep from 3 to 7 am ) followed by 8 weeks of evening bright white light for 60 min/d within 90 minutes of bedtime. We tested 17 P-M participants, 9 normal controls and 8 depressed participants (DPs) (by Diagnostic and Statistical Manual of Mental Disorders [Fifth Edition] criteria). Clinicians assessed mood by structured interviews and subjective mood ratings. Participants wore actigraphs to measure sleep and activity and collected overnight urine samples for the melatonin metabolite, 6-sulfatoxymelatonin (6-SMT), before, during, and after interventions. Baseline depressed mood correlated with delayed 6-SMT offset time (cessation of melatonin metabolite [6-SMT] secretion) ( r = +0.733, P = 0.038). After phase-advance intervention versus phase-delay intervention, 6-SMT offset (start of melatonin and 6-SMT decrease) was significantly advanced in DPs (mean ± SD, 2 h 15 min ± 12 min; P = 0.042); advance in 6-SMT acrophase (time of maximum melatonin and 6-SMT secretion) correlated positively with mood improvement ( r = +0.978, P = 0.001). Mood improved (+70%, P = 0.007) by both 2 and 8 weeks. These preliminary findings reveal significantly phase-delayed melatonin rhythms in DP versus normal control P-M women. Phase-advancing melatonin rhythms improves mood in association with melatonin advance. Thus, sleep-light interventions may potentially offer safe, rapid, nonpharmaceutical, well-tolerated, affordable home treatments for P-M depression.

Impact of repeated morning bright white light exposures on attention in a simulated office environment

Attention is essential to the work. This study investigated the effects of two different light pulses on a simple attention task. In addition, the effects of subsequent exposure to constant but different illuminance levels on the continuation of the simple attention task and a subsequent complex attention task were examined. A total of 56 subjects were assigned in random order to two white light interventions that were repeated five times during the morning. Each light intervention consisted of a brief light pulse followed by constant light exposure and differed in temporal dimming dynamics and corneal illuminance. Subjective and psychometric parameters were recorded several times during light exposure. Heart rate variability (HRV) was derived from continuous electrocardiograms. Subjects showed improved reaction speed in the simple attention task, accompanied by higher HRV under a brighter light pulse without habituation by repetition. This difference in simple attention performance disappeared when light exposure remained the same after the light pulse. In addition, higher reaction speed and HRV were observed in the complex attention task under constant bright light exposure. Intermittent bright light seems promising to acutely improve attentional performance in office workplaces. Future research is needed to investigate daytime light effects on other work-related cognitive functions.

0314 Late Evening Room Light and Sleep Restriction Reverses the Phase Advancing Effect of Bright Morning Light in Adolescents

Abstract Introduction Late bedtimes and sleep restriction are common during adolescence, particularly on school nights. We examined circadian phase advancing effects of bright morning light (ML) with increasing doses of evening room light exposure and sleep restriction due to late bedtimes. Methods Adolescents (n=38, 21 girls) aged 14.1 to 18.0 years completed a 14-day protocol during summer vacation. On days 1-7, they slept at home on individualized 10-h sleep/dark schedules. On days 8-14, they lived in the laboratory. On day 8, we measured their Dim Light Melatonin Onset (DLMO). On days 9 and 10, they were put to bed 1.5h (n=9), 3.0h (n=12), or 4.5h (n=8) later and kept awake in room light (104±11 lux at the angle of gaze). Wake time was unchanged; thus, sleep opportunity was shortened to 8.5h, 7h, and 5.5h, respectively. The fourth group (n=9) kept their baseline bedtime, were not exposed to any additional evening light (EL) and were not sleep restricted. On day 11, all groups were put to bed and awakened 1.5 h earlier and were exposed to intermittent bright ML (three 30-min exposures; 8599±885 lux). On each subsequent day (12 and 13), sleep and ML were advanced 1h. Thus, there were 3 days of a gradually advancing sleep schedule and bright ML. Final DLMO was measured on day 14. Results The 0h EL group showed a large DLMO advance (2.2±1.0 h), but the advance was reduced in the 1.5h EL group (0.5±0.6 h). DLMO delayed in the 3h EL group (-0.9±1.1 h). There was a large phase delay in the 4.5h EL group (-2.6±1.2 h). Phase shifts differed among all groups [F(3,34)=36.7, p&amp;lt;.001]. Conclusion Circadian rhythms of adolescents were advanced when they were exposed to bright ML and a gradually advancing sleep schedule, as shown in many studies of adults. However, when kept up later in ordinary room light, the same advancing sleep schedule and bright ML did not produce as much of an advance. Phase delay shifts occurred when bedtimes were 3h or 4.5h later. EL and sleep restriction can reverse the advancing effect of bright ML. Support (if any) R01 HL146772 (Crowley)

0112 Acute Sleep Restriction and Circadian Misalignment Impairs Attention in High School Students

Abstract Introduction We examined the impact of acute sleep restriction and circadian misalignment on reaction times in adolescents. Methods Adolescents (n=38, 21 girls) aged 14.1-18.0 years completed a 14-day protocol. On days 1-7, participants slept at home on individualized 10-h sleep/dark schedules. On days 8-14, they lived in the laboratory. On day 8, Dim Light Melatonin Onset (DLMO) was measured. On Days 9-13, sleep opportunity was restricted to 8.5h (n=9), 7h (n=12), or 5.5h (n=8). A fourth group was not sleep restricted a had a 10-h sleep opportunity (control; n=9). On days 11-13, sleep/dark gradually shifted earlier with morning bright light to advance circadian rhythms. Final DLMO was measured on day 14. Participants completed simple reaction time tasks on days 5 (baseline), 11 (after 2 sleep restriction (SR) nights = post-SR), and 13 (after 2 shifted sleep/dark nights = post-shift). Testing began 2.5h, 5.5h, 8.5h, and 11.5h after wake. Daily difference from baseline scores for post-SR lapses, median reaction time (MedRT), mean 1/RT (responses/sec), fastest 10% RT (F10), and slowest 10% 1/RT (S10) were compared between sleep opportunity groups. Final temperature minimum (Tmin) was estimated post-hoc (Final DLMO+7h). Tmin 2-4h before wake defined an aligned subgroup (N=16) and Tmin after wake defined a misaligned subgroup (N=10). Post-SR scores (day 11) were subtracted from post-shift scores (day 13) at corresponding times relative to wake. Aligned and misaligned subgroups were compared to determine the of impact circadian misalignment. Results Lapses [F(3,34)=3.8,p=.02] and MedRT [F(3,34=3.3,p=.03] increased from baseline in a SR-dose-dependent manner. Lapses and MedRT increased more with 7hSR (lapsesΔ=19.4±9.1; MedRTΔ=80.7±51.4 msec) and 5.5hSR (lapsesΔ=25.8±18.6; MedRTΔ=99.5±74.6 msec) compared to Control (lapsesΔ=5.4±4.8; MedRTΔ=20.8±21.7 msec). Mean 1/RT, F10, and S10 showed similar trends (p’s≤0.1). MedRT slowed [t(24)=2.24,p=0.04] and response rate decreased (Mean 1/RT: t(24)=2.06,p=.05; S10: t(24)=2.16,p=.04) in the misaligned compared to the aligned group 2.5h after wake. Conclusion Attention decrements occurred when sleep was restricted to 5.5h or 7h, the latter being a typical sleep opportunity for high school students. Circadian misalignment also contributed to decrements in morning attention, which has major implications for safety during the school commute and academics. Support (if any) R01 HL146772 (Crowley)

Sleep as a Therapeutic Target for Pain Management

The purpose of this review is to provide a summary of the utilization of sleep as a therapeutic target for chronic pain and to evaluate the recent literature on current and proposed pharmacologic and non-pharmacologic sleep interventions used in the management of pain disorders. Sleep is a promising therapeutic target in the treatment of pain disorders with both non-pharmacologic and pharmacologic therapies. Non-pharmacologic therapies include cognitive behavioral therapy and sensory-based therapies such as pink noise, audio-visual stimulation, and morning bright light therapy. Pharmacologic therapies include melatonin, z-drugs, gabapentinoids, and the novel orexin antagonists. However, more research is needed to clarify if these therapies can improve pain specifically by improving sleep. There is a vast array of investigational opportunities in sleep-targeted therapies for pathologic pain, and larger controlled, prospective trials are needed to fully elucidate their efficacy.

Bright Morning Lighting Enhancing Parasympathetic Activity at Night: A Pilot Study on Elderly Female Patients with Dementia without a Pacemaker.

Exposure to bright morning light (BML) entrains the master circadian clock, modulates physiological circadian rhythms, and reduces sleep-wake disturbances. However, its impact on the autonomic nervous system at night remains unclear. Here, we investigated the effects of BML exposure on parasympathetic nervous system (PSNS) and sympathetic nervous system (SNS) activity at night in elderly women. This nonrandomized controlled pilot study included female participants aged ≥ 60 years who were diagnosed with a type of dementia or cognitive disorder, excluding individuals with pacemakers. The treatment group was exposed to 2500 lx of BML, whereas the control group was exposed to 200 lx of general lighting. We measured heart rate variability to quantify ANS activity. The treatment group displayed significant increases in high-frequency (HF) power (Roy's largest root = 1.62; p < 0.001) and nonsignificant decreases in normalized low-frequency (LF%) power. The corresponding nonsignificant decreases in the low-frequency/high-frequency (LF/HF) ratio and cognitive function were correlated with PSNS activity (Roy's largest root = 1.41; p < 0.001), which improved severe dementia. BML exposure reduced SNS activity and enhanced PSNS activity at night in female participants, which improved cognitive function. Thus, BML therapy may be a useful clinical tool for alleviating cognitive decline.

Critically-timed sleep+light interventions differentially improve mood in pregnancy vs. postpartum depression by shifting melatonin rhythms

BackgroundTesting the hypothesis that combined wake + light therapy improves mood in pregnant vs. postpartum depressed participants (DP) by differentially altering melatonin and sleep timing. MethodsInitially 89 women, 37 pregnant (21 normal controls-NC; 16 DP) and 52 postpartum (27 NCs; 25 DP), were randomized to a parallel trial of a phase-delay intervention (PDI): 1-night of early-night wake therapy (sleep 3-7 am) + 6-weeks of evening bright white light (Litebook Advantage) for 60 min starting 90 min before bedtime, vs. a Phase-advance intervention (PAI): 1-night of late-night wake therapy (sleep 9 pm-1 am) + 6-weeks of morning bright white light for 60 min within 30 min of wake time. Blinded clinicians assessed mood weekly by structured interview, and participants completed subjective ratings, a Morningness-Eveningness questionnaire, actigraphy, and collected 2 overnight urine samples for 6-sulphatoxy melatonin (6-SMT). ResultsIn pregnant DP, mood improved more after the PDI vs. PAI (p = .016), whereas in postpartum DP, mood improved more after the PAI vs. PDI (p = .019). After wake therapy, 2 weeks of light treatment was as efficacious as 6 weeks (p > .05). In postpartum DP, PAI phase-advanced 6-SMT offset and acrophase (p < .05), which correlated positively with mood improvement magnitude (p = .003). LimitationsSmall N. ConclusionsMood improved more after 2 weeks of the PDI in pregnant DP, but more after 2 weeks of PAI in postpartum DP in which improvement magnitude correlated with 6-SMT phase-advance. Thus, critically-timed Sleep + Light Interventions provide safe, efficacious, rapid-acting, well-tolerated, at-home, non-pharmaceutical treatments for peripartum DP.

A 1-week sleep and light intervention improves mood in premenstrual dysphoric disorder in association with shifting melatonin offset time earlier

To test the hypothesis that 1 week of combined sleep and light interventions (SALI), which phase-advance (shift earlier) melatonin circadian rhythms, improves mood significantly more than phase-delay (shift later) SALI. After a 2-month diagnostic evaluation for premenstrual dysphoric disorder (PMDD per DSM-5 criteria) in a university clinical research setting, 44 participants enrolled in baseline studies were randomized in the luteal phase at home to (A) a phase-advance intervention (PAI): 1 night of late-night wake therapy (LWT: sleep 9 pm–1 am) followed by 7 days of the morning (AM) bright white light (BWL), or (B) a phase-delay intervention (PDI): 1 night of early-night wake therapy (EWT: sleep 3–7 am) plus 7 days of the evening (PM) BWL. After a month of no intervention, participants underwent the alternate intervention. Outcome measures were mood, the melatonin metabolite, 6-sulfatoxymelatonin (6-SMT), and actigraphy (to assess protocol compliance). At baseline, atypical depression correlated positively with phase delay in 6-SMT offset time (r = .456, p = .038). PAI advanced 6-SMT offset from baseline more than PDI (p < .05), and improved raw mood scores more than PDI (p < .05). As hypothesized, percent improvement in mood correlated positively with a phase advance from baseline in 6-SMT offset time (p < .001). Treatment with 1 night of advanced/restricted sleep followed by 7 days of AM BWL (PAI) was more efficacious in reducing PMDD depression symptoms than a PDI; mood improvement occurred in association with phase advance in 6-SMT offset time. Combined SALIs offer safe, efficacious, rapid-acting, well-tolerated, non-pharmacological, non-hormonal, affordable, repeatable home interventions for PMDD. Clinical Trials.gov NCT # NCT01799733.

A matter of time: A systematic scoping review on a potential role of the circadian system in binge eating behavior.

BackgroundEmerging research suggests that food intake timing, eating behavior and food preference are associated with aspects of the circadian system function but the role that the circadian system may play in binge eating (BE) behavior in humans remains unclear.ObjectiveTo systematically evaluate the evidence for circadian system involvement in BE behavior.MethodsSystematic searches of PubMed, EMBASE, and Scopus were performed for reports published from inception until May 2020 (PROSPERO Registration CRD42020186325). Searches were conducted by combining Medical Subject Headings related to the circadian system, BE behavior, and/or interventions. Observational and interventional studies in humans with BE behavior published in peer-review journals in the English language were included. Studies were assessed using quality and risk of bias tools (AXIS, ROB 2.0, or ROBINS).ResultsThe search produced 660 articles, 51 of which were included in this review. Of these articles, 46 were observational studies and 5 were interventional trials. Evidence from these studies suggests that individuals with BE behavior tend to have more food intake, more binge cravings, and more BE episodes later in the day. Hormonal and day/night locomotor activity rhythm disturbances may be associated with BE behavior. Furthermore, late diurnal preference (“eveningness”) was associated with BE behavior and chronobiological interventions that shift the circadian clock earlier (e.g., morning bright light therapy) were found to possibly decrease BE behavior. Substantive clinical overlap exists between BE and night eating behavior. However, there is a significant knowledge gap regarding their potential relationship with the circadian system. Limitations include the lack of studies that use best-established techniques to assess the chronobiology of BE behavior, heterogeneity of participants, diagnostic criteria, and study design, which preclude a meta-analytic approach.ConclusionCurrent evidence, although limited, suggests that the circadian system may play a role in the etiology of BE behavior. Further mechanistic studies are needed to fully characterize a potential role of the circadian system in BE behavior. A chronobiological approach to studying BE behavior may lead to identification of its neurobiological components and development of novel therapeutic interventions.Systematic review registration[https://www.crd.york.ac.uk/prospero/display_record.php?ID=CRD42020186325], identifier [CRD42020186325].

Circadian rhythms-related disorders in diurnal fat sand rats under modern lifestyle conditions: A review.

Modern lifestyle reduces environmental rhythmicity and may lead to circadian desynchrony. We are exposed to poor day-time lighting indoors and excessive night-time artificial light. We use air-conditioning to reduce ambient temperature cycle, and food is regularly available at all times. These disruptions of daily rhythms may lead to type 2 diabetes mellitus (T2DM), obesity, cardiometabolic diseases (CMD), depression and anxiety, all of which impose major public health and economic burden on societies. Therefore, we need appropriate animal models to gain a better understanding of their etiologic mechanisms, prevention, and management.We argue that the fat sand rat (Psammomys obesus), a diurnal animal model, is most suitable for studying the effects of modern-life conditions. Numerous attributes make it an excellent model to study human health disorders including T2DM, CMD, depression and anxiety. Here we review a comprehensive series of studies we and others conducted, utilizing the fat sand rat to study the underlying interactions between biological rhythms and health. Understanding these interactions will help deciphering the biological basis of these diseases, which often occur concurrently. We found that when kept in the laboratory (compared with natural and semi-wild outdoors conditions where they are diurnal), fat sand rats show low amplitude, nocturnal or arrhythmic activity patterns, dampened daily glucose rhythm, glucose intolerance, obesity and decreased survival rates. Short photoperiod acclimation exacerbates these pathologies and further dampens behavioral and molecular daily rhythms, resulting in CMD, T2DM, obesity, adipocyte dysfunction, cataracts, depression and anxiety. Increasing environmental rhythmicity by morning bright light exposure or by access to running wheels strengthens daily rhythms, and results in higher peak-to-trough difference in activity, better rhythmicity in clock genes expression, lower blood glucose and insulin levels, improved glucose tolerance, lower body and heart weight, and lower anxiety and depression. In summary, we have demonstrated that fat sand rats living under the correspondent of “human modern lifestyle” conditions exhibit dampened behavioral and biological rhythms and develop circadian desynchrony, which leads to what we have named “The Circadian Syndrome”. Environmental manipulations that increase rhythmicity result in improvement or prevention of these pathologies. Similar interventions in human subjects could have the same positive results and further research on this should be undertaken.

Shine light on sleep: Morning bright light improves nocturnal sleep and next morning alertness among college students.

The relationship between daytime light, especially morning light and sleep, has not been well documented. People who work in an office spend most of their time indoors and thus have less access to high-level daylight. The current study employed a field intervention approach to investigate whether exposure to 1.5h of bright electric light in the early morning for 1 workweek would benefit sleep among students who spent most of their time in an office at the university. Twelve students (24.92 ± 1.78 years) underwent a 2 workday baseline measurement and two inconsecutive 5 workday interventions (with 1 week washout) with morning bright light and regular office light (1000 lx, 6500 K vs. 300 lx, 4000 K, at eye level). The sleep outcomes were recorded with actigraphy and a sleep diary. In addition, self-ratings of daytime sleepiness, mood, mental fatigue, perceived effort, and next morning sleepiness were measured each workday. The results showed that exposure to morning bright light versus regular office light yielded a higher sleep efficiency (83.82% ± 1.60 vs. 80.35% ± 1.57, p=0.02), a smaller fragmentation index (15.26% ± 1.31 vs. 17.18% ± 1.28, p=0.05), and a shorter time in bed (7.12 ± 0.13 vs. 7.51 ± 0.12, p=0.03). Meanwhile, an earlier sleep onset time, shorter sleep latency, and lower morning sleepiness were observed after a 5 workday morning bright light intervention compared with the baseline (ps <0.05), no such benefit was found for self-ratings (ps >0.05). These findings support existing evidence that morning bright light could function as an enhancer of sleep and alertness for office occupants.

Feasibility and preliminary efficacy for morning bright light therapy to improve sleep and plasma biomarkers in US Veterans with TBI. A prospective, open-label, single-arm trial.

Mild traumatic brain injury (TBI) is associated with persistent sleep-wake dysfunction, including insomnia and circadian rhythm disruption, which can exacerbate functional outcomes including mood, pain, and quality of life. Present therapies to treat sleep-wake disturbances in those with TBI (e.g., cognitive behavioral therapy for insomnia) are limited by marginal efficacy, poor patient acceptability, and/or high patient/provider burden. Thus, this study aimed to assess the feasibility and preliminary efficacy of morning bright light therapy, to improve sleep in Veterans with TBI (NCT03578003). Thirty-three Veterans with history of TBI were prospectively enrolled in a single-arm, open-label intervention using a lightbox (~10,000 lux at the eye) for 60-minutes every morning for 4-weeks. Pre- and post-intervention outcomes included questionnaires related to sleep, mood, TBI, post-traumatic stress disorder (PTSD), and pain; wrist actigraphy as a proxy for objective sleep; and blood-based biomarkers related to TBI/sleep. The protocol was rated favorably by ~75% of participants, with adherence to the lightbox and actigraphy being ~87% and 97%, respectively. Post-intervention improvements were observed in self-reported symptoms related to insomnia, mood, and pain; actigraphy-derived measures of sleep; and blood-based biomarkers related to peripheral inflammatory balance. The severity of comorbid PTSD was a significant positive predictor of response to treatment. Morning bright light therapy is a feasible and acceptable intervention that shows preliminary efficacy to treat disrupted sleep in Veterans with TBI. A full-scale randomized, placebo-controlled study with longitudinal follow-up is warranted to assess the efficacy of morning bright light therapy to improve sleep, biomarkers, and other TBI related symptoms.