scholarly journals Beyond the limits of circadian entrainment: Non-24-hour sleep-wake disorder, shift work, and social jet lag

2021 ◽  
Author(s):  
Casey O Diekman ◽  
Amitabha Bose
Keyword(s):  
Shift Work ◽  
Bright Light ◽  
Light Therapy ◽  
Jet Lag ◽  
Mathematical Methods ◽  
Dark Cycle ◽  
Circadian Misalignment ◽  
Circadian Phase ◽  
Catch Up ◽  
Night Shifts

While the vast majority of humans are able to entrain their circadian rhythm to the 24-hour light-dark cycle, there are numerous individuals who are not able to do so due to disease or societal reasons. We use computational and mathematical methods to analyze a well-established model of human circadian rhythms to address cases where individuals do not entrain to the 24-hour light-dark cycle, leading to misalignment of their circadian phase. For each case, we provide a mathematically justified strategy for how to minimize circadian misalignment. In the case of non-24-hour sleep-wake disorder, we show why appropriately timed bright light therapy induces entrainment. With regard to shift work, we explain why reentrainment times following transitions between day and night shifts are asymmetric, and how higher light intensity enables unusually rapid reentrainment after certain transitions. Finally, with regard to teenagers who engage in compensatory catch-up sleep on weekends, we propose a rule of thumb for sleep and wake onset times that minimizes circadian misalignment due to this type of social jet lag. In all cases, the primary mathematical approach involves understanding the dynamics of entrainment maps that measure the phase of the entrained rhythm with respect to the daily onset of lights.

Morning bright light therapy: a helpful tool for reducing comorbid symptoms of affective and behavioral dysregulation in juvenile depressed inpatients? A pilot trial

2017 ◽  
Vol 45 (1) ◽  
pp. 34-41 ◽  
Author(s):  
Sarah Bogen ◽  
Tanja Legenbauer ◽  
Stephanie Gest ◽  
Martin Holtmann
Keyword(s):  
Pilot Trial ◽  
Secondary Analysis ◽  
Bright Light ◽  
Light Therapy ◽  
Bright Light Therapy ◽  
Circadian Phase ◽  
Behavioral Dysregulation ◽  
Sleep Parameters ◽  
Circadian Effect ◽  
Dysregulation Profile

Abstract. Objective: In recent years, bright light therapy (BLT) has been used to treat depression and to stabilize circadian rhythms. In this study we evaluated whether it is also helpful for comorbid symptoms of affective and behavioral dysregulation in depressive inpatients. Method: This article reports a secondary analysis comparing two subgroups of depressive participants with comorbid affective and behavioral dysregulation, captured with the dysregulation-profile of the Strengths and Difficulties Questionnaire (SDQ-DP; n = 16 vs. n = 11). Participants were randomly allocated to active BLT (10,000 lux) or control BLT (approx. 100 lux), and received 45 minutes of BLT for 2 weeks. SDQ-DP scores, sleep parameters, and circadian preference were assessed at baseline, after the intervention, and 3 weeks later. Results: No direct effects on SDQ-DP scores were observed. Sleep improved in both conditions. Only in the active BLT condition was a circadian phase advance found. Correlation and regression analyses indicated an indirect, circadian effect for improved SDQ-DP scores. Conclusions: The data of this pilot trial should be considered preliminary and merely descriptive. Further research is warranted.


Abstract 14384: Light Therapy Improves Circadian Blood Pressure Control and Glucose Homeostasis in Rotating Night Shift Workers via Mechanisms Independent of Melatonin

Circulation ◽  
2020 ◽  
Vol 142 (Suppl_3) ◽  
Author(s):  
Juliane Hannemann ◽  
Anika Laing ◽  
Benita Middleton ◽  
Jonathan Cridland ◽  
Bart Staels ◽  
...  
Keyword(s):  
Blood Pressure ◽  
Circadian Rhythms ◽  
Glucose Tolerance ◽  
Shift Work ◽  
Therapy Group ◽  
Night Shift ◽  
Light Therapy ◽  
Pressure Control ◽  
Shift Workers ◽  
Night Shifts

Introduction: Night shift work is associated with high rates of hypertension, heart disease, and metabolic syndrome. These cardiometabolic diseases have been linked to the disruption of circadian rhythms in night shift workers. Rotating night shift work is increasingly common in the working population worldwide. Hypothesis: We hypothesized that light therapy might help to normalize disrupted circadian rhythms and stabilize diurnal control of blood pressure and glucose tolerance in rotating night shift workers. Methods: We randomized 24 rotating night shift workers (mean age, 36±13 years, 7 males) who had spent a median of 6 years on rotating night shifts with a median of 6 night shifts/month to 12 weeks of light therapy (light during first half of each night shift and in the morning of off-work days) or no intervention and compared them with 12 daytime workers (37±11 years, 6 males). We measured oral glucose tolerance (OGTT), 24h blood pressure and arterial stiffness, and the circadian profiles of melatonin, cortisol, metanephrine and normetanephrine at baseline, after 12 weeks of intervention, and 12 weeks after the end of intervention. Results: At baseline, fewer night shift workers showed dipper status of blood pressure as compared to daytime workers (21% vs. 55%; p<0.001). After 12 weeks of light therapy, there was a highly significant increase in the proportion of dippers (to 42%; p<0.0001). We also observed a significant decrease in serum glucose during OGTT in the light therapy group (-22%; p<0.05), with no change in serum insulin. Whilst circadian profiles of melatonin and cortisol were unchanged, there was a significant reduction in nighttime plasma metanephrine and normetanephrine levels in the light therapy group (p<0.01). Conclusions: Chronotherapeutic light therapy significantly improves diurnal blood pressure control and glucose tolerance in rotating night shift workers. This effect is unrelated to mechanisms traditionally linked to the circadian clock like melatonin and cortisol, but it is paralleled by reduced catecholamine levels. Our data suggest that chronotherapeutic light therapy may improve the adjustment to atypical working hours in rotating night shift workers, thereby reducing stress and improving cardiometabolic function.

scholarly journals Light entrainment of the SCN circadian clock and implications for personalized alterations of corticosterone rhythms in shift work and jet lag

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Yannuo Li ◽  
Ioannis P. Androulakis
Keyword(s):  
Shift Work ◽  
Hpa Axis ◽  
Light Therapy ◽  
Light Sensitivity ◽  
Light Signal ◽  
Coupled Systems ◽  
Jet Lag ◽  
Trade Offs ◽  
Central Pacemaker ◽  
The Impact

AbstractThe suprachiasmatic nucleus (SCN) functions as the central pacemaker aligning physiological and behavioral oscillations to day/night (activity/inactivity) transitions. The light signal entrains the molecular clock of the photo-sensitive ventrolateral (VL) core of the SCN which in turn entrains the dorsomedial (DM) shell via the neurotransmitter vasoactive intestinal polypeptide (VIP). The shell converts the VIP rhythmic signals to circadian oscillations of arginine vasopressin (AVP), which eventually act as a neurotransmitter signal entraining the hypothalamic–pituitary–adrenal (HPA) axis, leading to robust circadian secretion of glucocorticoids. In this work, we discuss a semi-mechanistic mathematical model that reflects the essential hierarchical structure of the photic signal transduction from the SCN to the HPA axis. By incorporating the interactions across the core, the shell, and the HPA axis, we investigate how these coupled systems synchronize leading to robust circadian oscillations. Our model predicts the existence of personalized synchronization strategies that enable the maintenance of homeostatic rhythms while allowing for differential responses to transient and permanent light schedule changes. We simulated different behavioral situations leading to perturbed rhythmicity, performed a detailed computational analysis of the dynamic response of the system under varying light schedules, and determined that (1) significant interindividual diversity and flexibility characterize adaptation to varying light schedules; (2) an individual’s tolerances to jet lag and alternating shift work are positively correlated, while the tolerances to jet lag and transient shift work are negatively correlated, which indicates trade-offs in an individual’s ability to maintain physiological rhythmicity; (3) weak light sensitivity leads to the reduction of circadian flexibility, implying that light therapy can be a potential approach to address shift work and jet lag related disorders. Finally, we developed a map of the impact of the synchronization within the SCN and between the SCN and the HPA axis as it relates to the emergence of circadian flexibility.

Can short-wavelength depleted bright light during single simulated night shifts prevent circadian phase shifts?

2017 ◽  
Vol 61 ◽  
pp. 22-30 ◽  
Author(s):  
J. Regente ◽  
J. de Zeeuw ◽  
F. Bes ◽  
C. Nowozin ◽  
S. Appelhoff ◽  
...  
Keyword(s):  
Short Wavelength ◽  
Bright Light ◽  
Phase Shifts ◽  
Circadian Phase ◽  
Night Shifts

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

2017 ◽  
Vol 91 ◽  
pp. 105-110 ◽  
Author(s):  
Rachel E. Fargason ◽  
Aaron D. Fobian ◽  
Lauren M. Hablitz ◽  
Jodi R. Paul ◽  
Brittny A. White ◽  
...  
Keyword(s):  
Pilot Study ◽  
Bright Light ◽  
Light Therapy ◽  
Adhd Symptoms ◽  
Bright Light Therapy ◽  
Circadian Phase

scholarly journals 0006 The Role of Stress in Sleep in Night Shift Workers: Going Beyond Circadian Misalignment

SLEEP ◽  
2020 ◽  
Vol 43 (Supplement_1) ◽  
pp. A2-A3
Author(s):  
E Schaap ◽  
C Sagong ◽  
A S Cuamatzi Castelan ◽  
J Sayed ◽  
T Roth ◽  
...  
Keyword(s):  
Sleep Disturbance ◽  
Sleep Duration ◽  
Shift Work ◽  
Night Shift ◽  
Sleep Onset ◽  
Shift Workers ◽  
Circadian Misalignment ◽  
Circadian Phase ◽  
Falling Asleep ◽  
Dim Light

Abstract Introduction Despite a growing need for nighttime work, few studies have characterized the causes of sleep disturbance in night shift workers beyond circadian misalignment. Recent research suggest that high sleep reactivity to stress (a predisposition for sleep disturbance due to stress) may also lead to sleep difficulties in shift workers. This study investigated if sleep reactivity is an independent predictor of daytime sleep disturbances after controlling for circadian phase. Methods Night shift workers (N= 48) completed an 8 hour polysomnography (PSG) during the daytime following a night shift (9am - 4pm). Circadian phase was measured using melatonin assays of saliva samples collected over 24 hours under dim light (&lt;10 lux; Dim Light Melatonin Onset [DLMO]). Sleep reactivity was measured using the Ford Insomnia Response to Stress Test (FIRST). Linear regressions were conducted with PSG sleep parameters as outcome variables: difficulty falling asleep (Sleep Onset Latency [SOL] and Latency to Persistent Sleep [LPS]), difficulty staying asleep (Wake After Sleep Onset [WASO]), and sleep duration (Total Sleep Time [TST]). FIRST was tested as a predictor controlling for DLMO. Results After controlling for circadian phase, higher FIRST scores was associated with more difficulty staying asleep (WASO: t[45]=4.059, p&lt;0.001) and shorter sleep duration (TST: t[45] = -4.403, p&lt;0.0001), but not predictive of difficulty falling asleep (SOL: p&gt;0.05). However, higher FIRST scores did predict a longer latency to persistent sleep (LPS: t[45]=2.272, p&lt;0.05). Conclusion These results suggest that sleep reactivity to stress and circadian misalignment are independent processes that are both associated with disrupted daytime sleep in night shift workers. Given that night shift work can also cause psychosocial stress, treatments focused on circadian misalignment alone may not be sufficient. Our study highlights the need to consider sleep reactivity in the clinical management of shift work disorder. Support Support for this study was provided to PC by NHLBI (K23HL138166).

Efficacy of bright light and sleep/darkness scheduling in alleviating circadian maladaptation to night work

2001 ◽  
Vol 281 (2) ◽  
pp. E384-E391 ◽  
Author(s):  
Todd S. Horowitz ◽  
Brian E. Cade ◽  
Jeremy M. Wolfe ◽  
Charles A. Czeisler
Keyword(s):  
Shift Work ◽  
Night Shift ◽  
Bright Light ◽  
Night Work ◽  
Sleep Episode ◽  
Work Related ◽  
Before And After ◽  
Dim Light ◽  
Night Shifts ◽  
Better Than

We tested the hypothesis that circadian adaptation to night work is best achieved by combining bright light during the night shift and scheduled sleep in darkness. Fifty-four subjects participated in a shift work simulation of 4 day and 3 night shifts followed by a 38-h constant routine (CR). Subjects received 2,500 lux ( Bright Light) or 150 lux ( Room Light) during night shifts and were scheduled to sleep (at home in darkened bedrooms) from 0800 to 1600 ( Fixed Sleep) or ad libitum ( Free Sleep). Dim light melatonin onset (DLMO) was measured before and after the night shifts. Both Fixed Sleepand Bright Light conditions significantly phase delayed DLMO. Treatments combined additively, with light leading to larger phase shifts. Free Sleep subjects who spontaneously adopted consistent sleep schedules adapted better than those who did not. Neither properly timed bright light nor fixed sleep schedules were consistently sufficient to shift the melatonin rhythm completely into the sleep episode. Scheduling of sleep/darkness should play a major role in prescriptions for overcoming shift work-related phase misalignment.

scholarly journals Reading increases ocular illuminance during light treatment

2012 ◽  
Vol 24 (4) ◽  
pp. 339-342
Author(s):  
Aamar Sleemi ◽  
Mary A. Johnson ◽  
Kelly J. Rohan ◽  
Olaoluwa Okusaga ◽  
Timileyin Adediran ◽  
...  
Keyword(s):  
Seasonal Affective Disorder ◽  
Bright Light ◽  
Light Therapy ◽  
Complete Response ◽  
Light Treatment ◽  
Friedman Analysis ◽  
Circadian Phase ◽  
Reading Material ◽  
Randomized Design ◽  
Post Hoc

Abstract Background: Bright-light treatment is a safe and effective treatment for the management of winter seasonal affective disorder (SAD). In a recent study, we found that the relative duration of reading was positively associated with likelihood of remission after six weeks of light treatment. Methods: Two technicians measured the illuminance of a light box with a light meter directed towards the center of reading material that was placed on a table in front of the light box. The measurement was also performed after reading material was removed. The two measurements were performed in a randomized order. Friedman analysis of variance with Wilcoxon post-hoc tests were used to compare illuminance with vs. without reading. Results: The presence of the reading material increased illuminance by 470.93 lux (95% CI 300.10–641.75), p<0.0001. Limitations: This is a technical report done under conditions intended to mimic those of typical ambulatory light treatment as much as possible. Conclusions: As reading materials reflect light from the light box, reading during light therapy increases ocular illuminance. If confirmed by future studies using continuous recordings in randomized design, instructing SAD patients to read during light therapy may contribute to a more complete response to light treatment. The downside of specific relevance for students, is that reading, in particular, with bright light in the late evening/early night may induce or worsen circadian phase delay, adversely affecting health and functioning.

scholarly journals Feasibility and Efficacy of Bright Light Therapy in Depressed Adolescent Inpatients

2018 ◽  
Vol 46 (5) ◽  
pp. 423-429 ◽  
Author(s):  
Inken Kirschbaum-Lesch ◽  
Stephanie Gest ◽  
Tanja Legenbauer ◽  
Martin Holtmann
Keyword(s):  
Depressive Symptoms ◽  
Adolescent Depression ◽  
Sleep Problems ◽  
Bright Light ◽  
Light Therapy ◽  
Sufficient Evidence ◽  
Clinical Impression ◽  
Bright Light Therapy ◽  
Circadian Phase ◽  
Positive Effects

Abstract. Objective: Bright light therapy (BLT) has recently come into increasing focus in the treatment of adolescent depression, whereby light glasses today appear to be more feasible than light therapy boxes. This study investigated the feasibility and efficacy of 4 weeks of BLT with light glasses. It also analyzed whether a treatment duration of 4 weeks of BLT yields larger effects than the 2 weeks of BLT investigated in previous studies. Methods: This first open-label, single-arm, prospective clinical trial pursued a naturalistic approach: 39 inpatients aged 12–18 years with moderate or severe depression received 4 weeks of morning BLT with light glasses in addition to usual treatment. Depressive symptoms, sleep problems, circadian phase, and the clinical global impression were assessed at several timepoints. In a second analysis, the data of the present study were compared to those from a previous pilot trial. Results: Depressive symptoms, sleep problems, and the global clinical impression improved significantly after BLT with light glasses, whereas the circadian phase did not change over time. Light glasses showed similarly positive effects on sleep parameters and depressive symptoms as light boxes. Contrary to expectation, prolonging BLT to 4 weeks did not yield larger effects on depressive symptoms and sleep complaints compared to 2 weeks of intervention. Conclusions: Light glasses seem to be a feasible and highly acceptable method for the treatment of adolescent depression. Further randomized controlled trials are needed to obtain sufficient evidence regarding the efficacy of BLT as an add-on intervention to psychological and pharmacological approaches for adolescent depression.

282 Effect of circadian misalignment on the sleep of police officers across a series of night shifts

SLEEP ◽  
2021 ◽  
Vol 44 (Supplement_2) ◽  
pp. A113-A113
Author(s):  
Anastasi Kosmadopoulos ◽  
Laura Kervezee ◽  
Philippe Boudreau ◽  
Diane Boivin
Keyword(s):  
Police Officers ◽  
Work Conditions ◽  
Night Work ◽  
Circadian Misalignment ◽  
Daytime Sleep ◽  
Circadian Phase ◽  
Work Cycle ◽  
Before And After ◽  
A Cell ◽  
Night Shifts

Abstract Introduction Misalignment of behavior and circadian rhythms due to night work can impair sleep and waking function. While both simulated and field-based studies suggest that circadian adaptation to a nocturnal schedule is slow, the rates of adaptation in real-world shift-work conditions are still largely unknown. The aim of this study was to evaluate the extent of adaptation of 24-h rhythms in 6-sulfatoxymelatonin (aMT6s) and cortisol in police officers across night shifts and to compare their effect on sleep. Methods A total of 76 police officers (20 women; aged 32.3±5.5 years, mean±SD) from the province of Québec, Canada, participated in a field study comprising their 28- or 35-day work-cycle. Urine samples were collected for ~24-h before and after a series of 3–7 night shifts. Rhythms of urinary aMT6s were considered adapted if midpoints following night shifts occurred during participants’ average daytime sleep period. Cortisol was considered adapted if midpoints occurred within 2h of their average daytime sleep offset. Sleep was measured with actigraphy and sleep logs on a cell phone. Data were analyzed with circular and linear mixed-effects models. Results Analyses were based on a subset of 37 participants with rhythms of both hormones suitable for circadian phase assessment before and after their series of night shifts. After night shifts, the group acrophase of adapted rhythms (aMT6: n=11, cortisol: n=9) occurred significantly later than for non-adapted rhythms (aMT6s: 10.9 h vs. 3.4 h, p&lt;.001; cortisol: 14.9 vs. 9.9 h, p&lt;.001). Participants with adapted aMT6s rhythms obtained cumulatively more sleep per day throughout the series of shifts than those with non-adapted rhythms (average 6.4 h per day vs 5.8 h per day; p=.026). Conclusion Consistent with prior research, our results from both urinary aMT6s and cortisol midpoints indicate that a large proportion of police officers remained in a state of circadian misalignment following their night shifts. The minority of officers who adapted to night work were able to obtain more sleep across consecutive night shifts. Support (if any) Project funded by the Institut de Recherche Robert-Sauvé en Santé et en Sécurité du Travail (IRSST). A.K. received a postdoctoral fellowship from the Fonds de Recherche en Santé du Québec (FRQS).

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