Cecilie Lund Vestergaard

We live in a modern 24-hour society that never truly sleeps, and around 10 % of the adult population suffers from chronic sleep difficulties defined as insomnia (Pallesen et al., 2001). There is thus a pressing need for knowledge about what characterizes health-promoting sleep patterns. This article is a popular science summary of the doctoral dissertation: ”Sleep patterns and health. Investigating the significance of sleep duration and sleep variability” (2024), Norwegian University of Science and Technology (NTNU), Trondheim.

Background: The impact of light exposure on mental health is increasingly recognised. Modifying inpatient evening light exposure may be a low-intensity intervention for mental disorders, but few randomised controlled trials (RCTs) exist. We report a large-scale pragmatic effectiveness RCT exploring whether individuals with acute psychiatric illnesses experience additional benefits from admission to an inpatient ward where changes in the evening light exposure are integrated into the therapeutic environment. Methods and findings: From 10/25/2018 to 03/29/2019, and 10/01/2019 to 11/15/2019, all adults (≥18 years of age) admitted for acute inpatient psychiatric care in Trondheim, Norway, were randomly allocated to a ward with a blue-depleted evening light environment or a ward with a standard light environment. Baseline and outcome data for individuals who provided deferred informed consent were used. The primary outcome measure was the mean duration of admission in days per individual. Secondary outcomes were estimated mean differences in key clinical outcomes: Improvement during admission (The Clinical Global Impressions Scale–Improvement, CGI-I) and illness severity at discharge (CGI-S), aggressive behaviour during admission (Broset Violence Checklist, BVC), violent incidents (Staff Observation Aggression Scale-Revised, SOAS-R), side effects and patient satisfaction, probabilities of suicidality, need for supervision due to suicidality, and change from involuntary to voluntary admission. The Intent to Treat sample comprised 476 individuals (mean age 37 (standard deviation (SD) 13.3); 193 (41%) were male, 283 (59%) were female). There were no differences in the mean duration of admission (7.1 days for inpatients exposed to the blue-depleted evening light environment versus 6.7 days for patients exposed to the standard evening light environment; estimated mean difference: 0.4 days (95% confidence interval (CI) [−0.9, 1.9]; p = 0.523). Inpatients exposed to the blue-depleted evening light showed higher improvement during admission (CGI-I difference 0.28 (95% CI [0.02, 0.54]; p = 0.035), Number Needed to Treat for clinically meaningful improvement (NNT): 12); lower illness severity at discharge (CGI-S difference −0.18 (95% CI [−0.34, −0.02]; p = 0.029), NNT for mild severity at discharge: 7); and lower levels of aggressive behaviour (difference in BVC predicted serious events per 100 days: −2.98 (95% CI [−4.98, −0.99]; p = 0.003), NNT: 9). There were no differences in other secondary outcomes. The nature of this study meant it was impossible to blind patients or clinical staff to the lighting condition. Conclusions: Modifying the evening light environment in acute psychiatric hospitals according to chronobiological principles does not change duration of admissions but can have clinically significant benefits without increasing side effects, reducing patient satisfaction or requiring additional clinical staff. Trial registration: Clinicaltrials.gov NCT03788993; 2018 (CRISTIN ID 602154).

Background: To examine whether weekday-to-weekend sleep duration (WWD) difference and specific WWD patterns are associated with mental and somatic health and academic performance in a student population. Methods: This study utilized cross-sectional data from the SHoT-2018 survey which includes responses from 50,054 full-time university/college students in Norway. Participants completed online questionnaires and reported sleep duration separately for weekdays and weekends. Medium sleep duration was defined as 7 to 9 h, short sleep duration as < 7 h and long sleep duration as > 9 h. Regression analyses were used to examine whether the degree and patterns of WWD was associated with health-related outcomes and academic performance. Results: The mean age of the sample was 23.2 years and comprised of 68.8% women. Most students (81.7%) slept longer on weekends compared to weekdays and 30.0% of the students reported a mean sleep duration shorter than 7 h. WWD difference was positively associated with higher odds of overweight/obesity, dissatisfaction with life, psychological distress, somatic burden and failed study exam. Concerning WWD patterns, the odds of students reporting unfavorably on the outcomes were particularly high for those who slept short on both weekdays and weekends, while those who slept short on weekdays seemed to benefit from sleeping longer (“catching up”) on weekends. Conclusions: Overall, WWD was associated with adverse health outcomes for students. Short sleep duration both on weekday and weekend was associated with the most detrimental outcomes in terms of health and academic performance, while sleeping in on weekends may alleviate some of the detriments.

Background: The impact of light exposure on mental health is increasingly recognized. Modifying inpatient evening light exposure may be a low-intensity intervention for mental disorders, but few randomized controlled trials (RCTs) exist. We report a large-scale pragmatic effectiveness RCT exploring whether individuals with acute psychiatric illnesses experience additional benefits from admission to an inpatient ward where changes in the evening light exposure are integrated into the therapeutic environment. Methods and findings: All adults admitted for acute inpatient psychiatric care over eight months were randomly allocated to a ward with a blue-depleted evening light environment or a ward with standard light environment. Baseline and outcome data from individuals who provided deferred informed consent were used to analyze the primary outcome measure (differences in duration of hospitalization) and secondary measures (differences in key clinical outcomes). The Intent to Treat sample comprised 476 individuals (mean age 37; 41% were male). There were no differences in the mean duration of hospitalization (6.7 vs. 7.1 days). Inpatients exposed to the blue-depleted evening light showed higher improvement during admission (Clinical Global Impressions scale-Improvement: 0.28, 95% CI: 0.02 to 0.54; p=0.035, Number Needed to Treat for clinically meaningful improvement (NNT): 12); lower illness severity at discharge (Clinical Global Impressions Scale-Severity: –0.18, 95% CI: –0.34 to – 0.02; p=0.029, NNT for mild severity at discharge: 7); and lower levels of aggressive behaviour (Broset Violence Checklist difference in predicted serious events per 100 days: –2.98; 95% CI: –4.98 to –0.99; p=0.003, NNT: 9). Incidents of harm to self or others, side effects, and patient satisfaction did not differ between the lighting conditions. Conclusions: Modifying the evening light environment in acute psychiatric hospitals according to chronobiological principles does not change duration of hospitalizations, but can have clinically significant benefits without increasing side effects, reducing patient satisfaction or requiring additional clinical staff.

Background To examine whether weekday-to-weekend sleep duration difference (WWD) and specific WWD patterns are associated with mental and somatic health and academic performance in a large student population. Methods This study utilized cross-sectional data from the SHoT-2018 survey which includes responses from 50,054 full-time university/college students in Norway. Participants completed online questionnaires and reported sleep duration separately for weekdays and weekends. Medium sleep duration was defined as 7 to 9 hours, short sleep duration as < 7 hours and long sleep duration as > 9 hours. Regression analyses were used to examine whether the degree and patterns of WWD was associated with health-related outcomes and academic performance. Results The mean WWD was 1 hour and 19 minutes. WWD was positively associated with higher odds of overweight/obesity, dissatisfaction with life, psychological distress, somatic burden and failed study exam. Further, short sleepers (on weekdays or weekends, or both) generally had higher odds of overweight/obesity, dissatisfaction with life, psychological distress, somatic burden and failed study exam, compared to medium sleepers. The odds of students reporting unfavorably on the outcomes were particularly high for those who slept short on both weekdays and weekends, while those who slept short on weekdays seemed to benefit from sleeping longer ("catching up") on weekends. Conclusions Overall, WWD was associated with adverse health outcomes for students. Short sleep duration both on weekday and weekend was associated with the most detrimental outcomes in terms of health and academic performance, while sleeping in on weekends may alleviate some of the detriments.

Summary: Using data from 1721 participants in a community‐based randomized control trial of digital cognitive behavioural therapy for insomnia compared with patient education, we employed linear mixed modelling analyses to examine whether chronotype moderated the benefits of digital cognitive behavioural therapy for insomnia on self‐reported levels of insomnia severity, fatigue and psychological distress. Baseline self‐ratings on the reduced version of the Horne–Östberg Morningness–Eveningness Questionnaire were used to categorize the sample into three chronotypes: morning type (n = 345; 20%); intermediate type (n = 843; 49%); and evening type (n = 524; 30%). Insomnia Severity Index, Chalder Fatigue Questionnaire, and Hospital Anxiety and Depression Scale were assessed pre‐ and post‐intervention (9 weeks). For individuals with self‐reported morning or intermediate chronotypes, digital cognitive behavioural therapy for insomnia was superior to patient education on all ratings (Insomnia Severity Index, Chalder Fatigue Questionnaire, and Hospital Anxiety and Depression Scale) at follow‐up (p‐values ≤ 0.05). For individuals with self‐reported evening chronotype, digital cognitive behavioural therapy for insomnia was superior to patient education for Insomnia Severity Index and Chalder Fatigue Questionnaire, but not on the Hospital Anxiety and Depression Scale (p = 0.139). There were significant differences in the treatment effects between the three chronotypes on the Insomnia Severity Index (p = 0.023) estimated difference between evening and morning type of −1.70, 95% confidence interval: −2.96 to −0.45, p = 0.008, and estimated difference between evening and intermediate type −1.53, 95% confidence interval: −3.04 to −0.03, p = 0.046. There were no significant differences in the treatment effects between the three chronotypes on the Chalder Fatigue Questionnaire (p = 0.488) or the Hospital Anxiety and Depression Scale (p = 0.536). We conclude that self‐reported chronotype moderates the effects of digital cognitive behavioural therapy for insomnia on insomnia severity, but not on psychological distress or fatigue.

Digital cognitive behavioral therapy for insomnia (dCBT-I) is an effective treatment for insomnia. However, less is known about mediators of its benefits. The aim of the present study was to test if intraindividual variability in sleep (IIV) was reduced with dCBT-I, and whether any identified reduction was a mediator of dCBT-I on insomnia severity and psychological distress. In a two-arm randomized controlled trial (RCT), 1720 adults with insomnia (dCBT-I = 867; patient education about sleep = 853) completed the Insomnia Severity Index (ISI), the Hospital Anxiety and Depression Scale (HADS) and sleep diaries, at baseline and 9-week follow-up. Changes in IIV were analyzed using linear mixed modeling followed by mediation analyses of ISI, HADS, and IIV in singular sleep metrics and composite measures (behavioral indices (BI-Z) and sleep disturbance indices (SI-Z)). dCBT-I was associated with reduced IIV across all singular sleep metrics, with the largest between-group effect sizes observed for sleep onset latency (SOL). Reduced IIV for SOL and wake after sleep onset had the overall greatest singular mediating effect. For composite measures, SI-Z mediated change in ISI (b = −0.74; 95% confidence interval (CI) −1.04 to −0.52; 13.3%) and HADS (b = −0.40; 95% CI −0.73 to −0.18; 29.2%), while BI-Z mediated minor changes. Reductions in IIV in key sleep metrics mediate significant changes in insomnia severity and especially psychological distress when using dCBT-I. These findings offer important evidence regarding the therapeutic action of dCBT-I and may guide the future development of this intervention. Name: Overcoming Insomnia: Impact on Sleep, Health and Work of Online CBT-I Registration number: NCT02558647 URL: https://clinicaltrials.gov/ct2/show/NCT02558647?cond=NCT02558647&draw=2&rank=1