Feasibility and impact on daytime sleepiness of an experimental protocol inducing variable sleep duration in adolescents

Sleep Hygiene Among Adolescents Clinically Referred to Behavioral Sleep Medicine: Comparisons to the Validation Sample and Associations with Sleep Problems

OBJECTIVES

1) Compare the sleep hygiene of our clinical sample to the community-based validation sample and established clinical thresholds and 2) clarify the relationship between sleep hygiene and sleep problems in adolescents referred for Behavioral Sleep Medicine (BSM) treatment.

METHODS

Clinical participants included BSM patients aged 11-18 years (n = 354) with insomnia. Adolescents completed the Adolescent Sleep Hygiene Scale (ASHS) and the Pediatric Insomnia Severity Index. Caregivers completed the Sleep Disorders Inventory for Students. Independent samples t-tests compared sleep hygiene between our clinical sample and the community-based ASHS validation sample (572 American adolescents). We report which sleep hygiene subscales fell below thresholds indicating clinically significant problems. Multiple linear regressions determined whether demographics and sleep hygiene subscales predicted sleep problems.

RESULTS

Adolescents referred to our BSM clinic had better overall sleep hygiene than the community-based validation sample, p < .001. They had inadequate sleep hygiene practices related to sleep stability, behavioral arousal, and cognitive/emotional arousal. Demographics and sleep hygiene factors significantly predicted both adolescent-reported insomnia severity and caregiver-reported sleep disturbance, ps < 0.001.

CONCLUSION

Poor sleep hygiene may result from maladaptive coping and can compound existing sleep problems. It is important to have consistent definitions of sleep hygiene that limit overlap with other key intervention targets.

Objective and Subjective Intraindividual Variability in Sleep: Predisposing Factors and Health Consequences

OBJECTIVE

We investigated the factors that predispose or precipitate greater intraindividual variability (IIV) in sleep. We further examined the potential consequences of IIV on overall sleep quality and health outcomes, including whether these relationships were found in both self-reported and actigraphy-measured sleep IIV.

METHODS

In Study 1, 699 US adults completed a Sleep Intra-Individual Variability Questionnaire and self-reported psychosocial, sleep quality, and health outcomes. In Study 2, 100 university students wore actigraphy and completed psychosocial, sleep, and health surveys at multiple timepoints.

RESULTS

In cross-sectional analyses that controlled for mean sleep duration, predisposing/precipitating factors to greater IIV were being an underrepresented racial/ethnic minority (Study 1: F = 13.95, p < .001; Study 2: F = 7.03, p = .009), having greater stress (Study 2: r values ≥ 0.32, p values ≤ .002) or trait vulnerability to stress (Study 1: r values ≥ 0.15, p values < .001), and showing poorer time management (Study 1: r values ≤ -0.12, p values ≤ .004; Study 2: r values ≤ -0.23, p values ≤ .028). In addition, both studies showed that greater sleep IIV was associated with decreased overall sleep quality, independent of mean sleep duration (Study 1: r values ≥ 0.20, p values < .001; Study 2: r values ≥ 0.33, p values ≤ .001). Concordance across subjective and objective IIV measures was modest ( r values = 0.09-0.35) and similar to concordance observed for subjective-objective mean sleep duration measures.

CONCLUSION

Risk for irregular sleep patterns is increased in specific demographic groups and may be precipitated by, or contribute to, higher stress and time management inefficiencies. Irregular sleep may lead to poor sleep quality and adverse health outcomes, independent of mean sleep duration, underscoring the importance of addressing sleep consistency.

Extending weeknight sleep of delayed adolescents using weekend morning bright light and evening time management

STUDY OBJECTIVES

Shift sleep onset earlier and extend school-night sleep duration of adolescents.

METHODS

Forty-six adolescents (14.5-17.9 years; 24 females) with habitual short sleep (≤7 h) and late bedtimes (≥23:00) on school nights slept as usual for 2 weeks (baseline). Then, there were three weekends and two sets of five weekdays in between. Circadian phase (Dim Light Melatonin Onset, DLMO) was measured in the laboratory on the first and third weekend. On weekdays, the "Intervention" group gradually advanced school-night bedtime (1 h earlier than baseline during week 1; 2 h earlier than baseline during week 2). Individualized evening time management plans ("Sleep RouTeen") were developed to facilitate earlier bedtimes. On the second weekend, Intervention participants received bright light (~6000 lux; 2.5 h) on both mornings. A control group completed the first and third weekend but not the second. They slept as usual and had no evening time management plan. Weekday sleep onset time and duration were derived from actigraphy.

RESULTS

Dim light melatonin onset (DLMO) advanced more in the Intervention (0.6 ± 0.8 h) compared to the Control (-0.1 ± 0.8 h) group. By week 2, the Intervention group fell asleep 1.5 ± 0.7 h earlier and sleep duration increased by 1.2 ± 0.7 h; sleep did not systematically change in the Control group.

CONCLUSIONS

This multi-pronged circadian-based intervention effectively increased school-night sleep duration for adolescents reporting chronic sleep restriction. Adolescents with early circadian phases may only need a time management plan, whereas those with later phases probably need both time management and morning bright light.

CLINICAL TRIALS

Teen School-Night Sleep Extension: An Intervention Targeting the Circadian System (#NCT04087603): https://clinicaltrials.gov/ct2/show/NCT04087603.

A developmental perspective on sleep consistency: Preschool age through emerging adulthood

OBJECTIVE/BACKGROUND

Beyond sleep duration, the regularity of sleep patterns (e.g., sleep consistency), including variability in sleep timing (e.g., bedtime, wake time) and duration, is a critical marker of sleep health. Sleep consistency is captured using a variety of methods within the literature (e.g., sleep intraindividual variability, social jetlag), but most of the research focuses on adolescents.

METHODS

Drawing on a developmental perspective, this narrative review highlights how normative changes at the individual (e.g., biological, cognitive, and social) and contextual (e.g., home, school, sociocultural) levels may contribute to inconsistent sleep patterns across development.

RESULTS AND CONCLUSIONS

This review emphasizes how inconsistent sleep may increase across pivotal transitions throughout development (e.g., elimination of naps, puberty, summertime, entering college). Finally, recommendations for measuring sleep consistency and areas to address in future research are discussed.

Too Jittery to Sleep? Temporal Associations of Actigraphic Sleep and Caffeine in Adolescents

Caffeine consumption has been linked to poor sleep health in adolescents, but it is unknown whether poor sleep predicts caffeine consumption, and/or whether caffeine consumption predicts poor sleep, particularly when sleep is measured objectively. Data were collected from a micro-longitudinal sub-study of the age 15 wave of the Fragile Families and Child Wellbeing Study (n = 589). Adolescents wore an actigraphy device and completed daily surveys for ~1 week. Daily surveys assessed subjective sleep quality and caffeinated beverage consumption (0 = no caffeine, 1 = any caffeine). Separate mixed models assessed whether actigraphy-measured sleep duration, timing, maintenance efficiency, and subjective quality predicted next-day caffeinated beverage consumption within and between adolescents. Variability (standard deviation) of sleep duration and timing, sleep regularity index, and social jetlag were tested as additional between-person predictors. Lagged models tested whether daily caffeinated beverage consumption predicted sleep that night (n = 458). Adolescents with more variable sleep duration and midpoint had higher average odds of consuming caffeinated beverages compared to others. After adolescents consumed ≥1 caffeinated beverage, they had later sleep onset that night and wake time the next morning than usual versus when they did not consume caffeine. Curbing caffeinated beverage consumption may aid in the maintenance of regular sleep schedules and advance sleep timing in adolescents.

Sleepiness is a signal to go to bed: data and model simulations

Study Objectives

Assess the validity of a subjective measure of sleepiness as an indicator of sleep drive by quantifying associations between intraindividual variation in evening sleepiness and bedtime, sleep duration, and next morning and subsequent evening sleepiness, in young adults.

Methods

Sleep timing and sleepiness were assessed in 19 students in late autumn and late spring on a total of 771 days. Karolinska Sleepiness Scales (KSS) were completed at half-hourly intervals at fixed clock times starting 4 h prior to participants’ habitual bedtime, and in the morning. Associations between sleepiness and sleep timing were evaluated by mixed model and nonparametric approaches and simulated with a mathematical model for the homeostatic and circadian regulation of sleepiness.

Results

Intraindividual variation in evening sleepiness was very large, covering four or five points on the 9-point KSS scale, and was significantly associated with subsequent sleep timing. On average, a one point higher KSS value was followed by 20 min earlier bedtime, which led to 11 min longer sleep, which correlated with lower sleepiness next morning and the following evening. Associations between sleepiness and sleep timing were stronger in early compared to late sleepers. Model simulations indicated that the directions of associations between sleepiness and sleep timing are in accordance with their homeostatic and circadian regulation, even though much of the variance in evening sleepiness and details of its time course remain unexplained by the model.

Conclusion

Subjective sleepiness is a valid indicator of the drive for sleep which, if acted upon, can reduce insufficient sleep.

Neurobehavioural functions during variable and stable short sleep schedules

We investigated whether variable sleep schedules might mitigate the neurobehavioural deficits induced by multiple nights of sleep restriction. In this 4-night experiment, 78 young adults (age: 18-28 years) were randomly assigned to four groups: 8888, 8666, 8846 and 8486, where each digit corresponded to time-in-bed in hours for each study night. After one baseline night of 8-hr time-in-bed, time-in-bed remained unchanged for the 8888 group, while the other groups had short sleep schedules (total time-in-bed = 18 hr) that differed in the number of time-in-bed changes. Sleep was monitored using actigraphy at home. Daytime neurobehavioural functions were assessed in the laboratory at single time points, after the baseline night, and again after 3 nights of the sleep manipulation period. For sustained attention, the 8888 group responded faster in the Psychomotor Vigilance Task after the manipulation period (p = .01), while responses became slower for the less variable sleep schedules (8666 and 8846; p < .01), but not the most variable sleep schedule (8486; p = .14). Processing speed also improved in the 8888 group and the variable 8846 and 8486 groups (p < .01), but not in the stable 8666 group (p = .09). Furthermore, subjective sleepiness was preserved in the 8888 and, importantly, 8486 groups (p > .05), but was elevated in the 8666 and 8846 groups (p < .05). These findings suggest that when sleep opportunities are limited across multiple nights, a variable sleep schedule that allows for prophylactic and/or recovery sleep on some nights may mitigate some daytime neurobehavioural deficits as compared with a schedule with no opportunity for recovery.