Sleep Extension Research Articles

The Effect of Acute Sleep Extension on Blood Pressure Is Dependent on the Change in Sleep Efficiency.

The present study investigated the effect of acute sleep extension on blood pressure and microvascular vasodilation. Sleep and daily physical activity were objectively measured at home for two weeks using wrist actigraphy in 22 adults (60 ± 15 y). Vascular measurements were made in the morning on the 8th and 15th day. Participants spent at least 10 h in bed on the night prior to one of these testing days to extend sleep. Mean arterial blood pressure (MAP) and peak reactive hyperemia in the forearm were measured on each testing day. Reactive hyperemia and MAP were unaltered (p > 0.05) by sleep extension in the total sample. However, adults who experienced improved sleep efficiency with sleep extension (n = 10, 4.2 ± 1.4%) exhibited reduced MAP (-5.5 ± 4.6 mm Hg, p = 0.005) while adults who had little change or decreased sleep efficiency (n = 12, -1.7 ± 2.9%) showed no change in MAP. The reduction in MAP was significantly different between sleep efficiency groups (p = 0.005, Hedges' g = 1.21) after adjustment for sex and moderate-to-vigorous physical activity. The results of this study suggest that sleep extension has the potential to reduce blood pressure in midlife to older adults when the additional sleep time improves the quality of sleep.

Gratitude, flourishing and prosocial behaviors following experimental sleep restriction and sleep extension

ABSTRACT People who are grateful, resilient and flourishing in life show better health, including better sleep. This correlational finding is typically attributed to personality factors or to positive outlooks causing better sleep. We investigated the reverse causal interpretation: do sleep losses and sleep gains experimentally affect feelings and expressions of gratitude, resilience and flourishing? Young adults (N = 90) were randomly assigned to sleep restriction, sleep extension or to sleep normally while wearing wristband actigraphy between Monday and Friday study sessions. State-level measures of flourishing, resilience and gratitude improved across the week with sleep extension and worsened with sleep restriction (ηp 2 = .13 to .17). Trait-level measures showed modest or no changes. Sleep-extended participants wrote twice as many details on their gratitude list as the other two conditions (ηp 2 = .11). Most effects persisted when accounting for mood. Therefore, subtle changes in nighttime sleep causally influence the components that underlie mental well-being.

Behavioral Intervention that Extends Sleep Duration Leads to Greater Self-Control in School-Aged Children.

Short sleep and evening phase preference associate with impaired self-control, yet few studies have assessed the efficacy of sleep extension for improving this behavioral domain. Thus, this secondary analysis of a behavioral sleep intervention measured whether an intervention that enhanced children's sleep also affected self-control. Differences by chronotype were also explored. Sixty-seven children (8-11 yr), who reportedly slept <9.5 hr/d, were randomized to either a control or sleep intervention condition (i.e., 4-session behavioral intervention to enhance sleep by 1-1.5 hr/night). Chronotype was assessed using the Child Chronotype Questionnaire at baseline, and self-control was assessed using the Self-Control Rating Scale (SCRS, a caregiver report) at baseline and 8 weeks postrandomization. Total sleep time (TST) was measured using wrist actigraphy for 1 week at both baseline and 8 weeks postrandomization. Partial correlations and mixed-model ANOVAs were used for statistical analyses, with age as a covariate. At baseline, children with shorter TST (r = -0.29, p = 0.02) and an evening preference (r = 0.26, p = 0.049) were perceived as having lower self-control by their caregivers. Significant condition*time interaction effects were found for TST ( p < 0.001) and SCRS score ( p = 0.046): From baseline to follow-up, children randomized to the sleep intervention exhibited a significant increase in TST and were perceived as having greater self-control by their caregiver; children randomized to the control condition exhibited no change in TST or in SCRS score. The condition*chronotype*time interaction effect was not significant. A brief sleep intervention that enhanced TST also resulted in enhanced caregiver reported self-control in school-age children. Results add to the growing evidence for the importance of sleep health in children.

The Effects of Experimental Sleep Extension in Middle-to-Older-Aged Healthy Sleepers

Abstract Objectives To determine the feasibility for middle-aged and older adults to extend their time in bed by 2 h per night for 3 consecutive weeks. Other aims were to examine the effects of sleep extension on mood, cognitive performance, and cardiovascular health. Methods Ten healthy middle-aged to older adults (9 women; M = 65.20 ± 4.78 years) who reported regularly sleeping 6 to 8 h per night participated in a randomized controlled cross-over study: 3 weeks of both habitual sleep and extended sleep (1-week recovery between treatments). Participants were asked to spend 2 additional hours in bed per night during sleep extension. Cognitive (e.g., errors, response time), psychological (e.g., depression, anxiety, mood), and physiological measures (e.g., inflammation, glucose, triglycerides, blood pressure) were assessed. Results Compared with habitual sleep, time in bed increased 81.63 ± 33.11 min and total sleep time increased 66.33 ± 28.64 min during sleep extension; these variables did not significantly change during baseline or the habitual sleep treatment. No significant treatment differences were found in the cognitive, psychological, or physiological measures. Discussion Neither significant positive nor negative effects of sleep extension were found for any of the variables. In terms of feasibility, it was difficult for the participants to extend their time in bed and, subsequently, attain more sleep by the targeted amount. Sleep extension by a greater degree or longer period of times might be more likely to elicit positive or negative effects.

Losing sleep influences dietary intake in children: a longitudinal compositional analysis of a randomised crossover trial

BackgroundAlthough inadequate sleep increases the risk of obesity in children, the mechanisms remain unclear. The aims of this study were to assess how sleep loss influenced dietary intake in children while accounting for corresponding changes in sedentary time and physical activity; and to investigate how changes in time use related to dietary intake.MethodsA randomized crossover trial in 105 healthy children (8–12 years) with normal sleep (~ 8–11 h/night) compared sleep extension (asked to turn lights off one hour earlier than usual for one week) and sleep restriction (turn lights off one hour later) conditions, separated by a washout week. 24-h time-use behaviors (sleep, wake after sleep onset, physical activity, sedentary time) were assessed using waist-worn actigraphy and dietary intake using two multiple-pass diet recalls during each intervention week. Longitudinal compositional analysis was undertaken with mixed effects regression models using isometric log ratios of time use variables as exposures and dietary variables as outcomes, and participant as a random effect.ResultsEighty three children (10.2 years, 53% female, 62% healthy weight) had 47.9 (SD 30.1) minutes less sleep during the restriction week but were also awake for 8.5 (21.4) minutes less at night. They spent this extra time awake in the day being more sedentary (+ 31 min) and more active (+ 21 min light physical activity, + 4 min MVPA). After adjusting for all changes in 24-h time use, losing 48 min of sleep was associated with consuming significantly more energy (262 kJ, 95% CI:55,470), all of which was from non-core foods (314 kJ; 43, 638). Increases in sedentary time were related to increased energy intake from non-core foods (177 kJ; 25, 329) whereas increases in MVPA were associated with higher intake from core foods (72 kJ; 7,136). Changes in diet were greater in female participants.ConclusionLoss of sleep was associated with increased energy intake, especially of non-core foods, independent of changes in sedentary time and physical activity. Interventions focusing on improving sleep may be beneficial for improving dietary intake and weight status in children.Trial RegistrationAustralian New Zealand Clinical Trials Registry ANZCTR ACTRN12618001671257, Registered 10th Oct 2018, https://www.anzctr.org.au/Trial/Registration/TrialReview.aspx?id=367587&isReview=true

Circadian misalignment proxies, BMI, and chronic conditions: the role for weekday to weekend sleep differences.

To evaluate whether social jet lag (SJL) and weekend catch-up sleep (CUS), proxies of circadian misalignment, were associated with BMI and chronic conditions. Participants (n = 2,050,18-65y) were part of a virtual cross-sectional and population-based research. We examined CUS and SJL as continuous and categorical (< 1h,1-2h, > 2h). Linear regression analyses were performed to assess the differences in BMI (outcome) associated with CUS and SJL. Restricted cubic splines were performed to explore the shape of the relationship between weekday-to-weekend variability in sleep duration, midpoint, wake time, and bedtime. Logistic regression models were used to estimate ORs(95%CIs) for chronic conditions and overweight related to CUS and SJL. Analyses were adjusted for sleep duration, biological and behavior-related variables. We found a positive association of SJL and CUS with BMI. The effects remained even after adjustment for weekly sleep duration and demonstrated a proportional increase with the magnitude of sleep variability. Among participants with SJL > 2h, BMI increased by 2.29kg/m2 (95%CI:0.84;3.74,p:0.002). They also had 129% higher odds of chronic conditions (95%CI:1.16;4.52, p:0.01) and 119% higher odds of overweight (95%CI: 1.20;3.98,p:0.01). Individuals with CUS > 2h presented 78% higher odds of overweight (95%CI:1.27;2.50,p:0.001) and an increase of 1.61kg/m2 in BMI (95%CI: 0.81; 2.40,p < 0.001). Our findings, which demonstrate that even a slight weekend sleep extension and variability of just 1h is associated with higher values of BMI, suggest incorporating measures for sleep consistency and regularity into clinical protocols and public health guidelines to prevent and treat obesity and related diseases.

Predictors of adherence to a brief sleep extension protocol in emerging adults.

This study examined how mental health symptoms (i.e., depression, anxiety, stress) and baseline sleep characteristics (i.e., sleep quality and levels of daytime sleepiness) predicted adherence to and initial success of a brief sleep extension research protocol in emerging adults. 184 emerging adults (ages 18-25; M = 20.96, SD = 2.04) were asked to extend their nightly sleep opportunity to 8hr for 1 week and to anchor bedtime and waketime. Sleep outcomes (adherence and initial protocol success) were tracked using actigraphy. Baseline sleep quality, daytime sleepiness, depression, anxiety, and stress were assessed using self-report questionnaires. Poorer baseline sleep quality predicted better adherence to the protocol (p = .002). Other baseline sleep characteristics and mental health were not predictive of adherence (ps>.50). Lower levels of baseline daytime sleepiness approached significance in predicting greater initial protocol success following the protocol (p = .05). Baseline sleep quality and mental health did not predict initial protocol success (ps > 0.34). Mental health symptoms did not significantly predict adherence to or the success of a sleep extension protocol. Surprisingly, individuals with poor baseline sleep quality were more likely to adhere to the extension protocol, perhaps suggesting heightened motivation for change or increased risk for sleep problems. This research provides valuable insight into factors that predict adherence to sleep extension protocols in emerging adults.

Sleep extension among adolescents promotes positive, goal-directed emotional responses during social interactions: a Pilot study

ABSTRACT The protective nature of adequate sleep during adolescence is poorly understood, particularly regarding social relationships. We explored emotion and behaviour during two social interaction tasks among teens assigned to sleep extension (SE) or typical sleep (TS) conditions. Twenty healthy adolescents completed a baseline assessment (7 nights typical sleep) followed by assignment to SE or TS (5 nights). Participants returned to the lab to complete a frustrating computer game and two social interactions with a confederate peer (one naturalistic, one manipulated) during which adolescents were asked to up-regulate positive emotion. Following a frustrating task, the SE group reported increased positive emotions during the goal-directed interaction relative to both the naturalistic interaction and the TS group. Findings suggest another 30 minutes of sleep for five nights assisted adolescents in up-regulating positive emotional to meet socially relevant goals. Findings from this pilot study support the protective role of adequate sleep for social functioning and emotional health during adolescence.

Reducing crash risk for young drivers: Protocol for a pragmatic randomised controlled trial to improve young driver sleep

BackgroundRoad trauma is a leading cause of death and disability for young Australians (15–24 years). Young adults are overrepresented in crashes due to sleepiness, with two-thirds of their fatal crashes attributed to sleepy driving. This trial aims to examine the effectiveness of a sleep extension and education program for improved road safety in young adults. MethodsYoung adults aged 18–24 years (n = 210) will be recruited for a pragmatic randomised controlled trial employing a placebo-controlled, parallel-groups design. The intervention group will undergo sleep extension and receive education on sleep, whereas the placebo control group will be provided with information about diet and nutrition. The primary outcomes of habitual sleep and on-road driving performance will be assessed via actigraphy and in-vehicle accelerometery. A range of secondary outcomes including driving behaviours (driving simulator), sleep (diaries and questionnaire) and socio-emotional measures will be assessed. DiscussionSleep is a modifiable factor that may reduce the risk of sleepiness-related crashes. Modifying sleep behaviour could potentially help to reduce the risk of young driver sleepiness-related crashes. This randomised control trial will objectively assess the efficacy of implementing sleep behaviour manipulation and education on reducing crash risk in young adult drivers.

Shared genetic architecture and causal relationship between sleep behaviors and lifespan

Poor sleep health is associated with a wide array of increased risk for cardiovascular, metabolic and mental health problems as well as all-cause mortality in observational studies, suggesting potential links between sleep health and lifespan. However, it has yet to be determined whether sleep health is genetically or/and causally associated with lifespan. In this study, we firstly studied the genome-wide genetic association between four sleep behaviors (short sleep duration, long sleep duration, insomnia, and sleep chronotype) and lifespan using GWAS summary statistics, and both sleep duration time and insomnia were negatively correlated with lifespan. Then, two-sample Mendelian randomization (MR) and multivariable MR analyses were applied to explore the causal effects between sleep behaviors and lifespan. We found that genetically predicted short sleep duration was causally and negatively associated with lifespan in univariable and multivariable MR analyses, and this effect was partially mediated by coronary artery disease (CAD), type 2 diabetes (T2D) and depression. In contrast, we found that insomnia had no causal effects on lifespan. Our results further confirmed the negative effects of short sleep duration on lifespan and suggested that extension of sleep may benefit the physical health of individuals with sleep loss. Further attention should be given to such public health issues.

Sleepy without stimulation: subjective and objective sleepiness in actigraphy-verified natural short sleepers.

Natural short sleepers (NSS)-individuals who report minimal sleepiness or daytime dysfunction despite habitually sleeping less than the recommended amount (i.e., <7 h)-are a focus of growing interest in sleep research. Yet, the predominance of research on NSS has relied on subjective reports of functionality. The present study examined subjective and objective sleepiness among actigraphy-verified NSS in comparison with recommended (7-9 h/day) length sleepers (RLS) who reported similarly minimal daytime dysfunction. The study tested the hypothesis that under conditions of low environmental stimulation, NSS have increased risk of drowsiness and sleep onset, regardless of perceived alertness. The NSS and RLS groups were identified via screening and verified with a 14 day assessment with actigraphy, sleep diaries, and morning ratings of sleep restoration. In-laboratory resting electroencephalography (EEG) data were analysed using a computerised EEG-based algorithm (Vigilance Algorithm Leipzig; VIGALL) to classify second-by-second changes in objective sleepiness ranging from cognitively active alertness to sleep onset. Results demonstrated that NSS exhibited significantly higher drowsiness and sleep onset ('microsleeps') across 15 min of resting EEG despite perceptions of lower subjective sleepiness compared to RLS. Findings suggest that irrespective of perceived sleep restoration and alertness, NSS appear to be at high risk of objective sleepiness that is rapidly unmasked under conditions of low environmental stimulation. Such apparent discrepancy between subjective and objective sleepiness has potentially important public health implications. Future research directions, including tests of mechanisms and tailored sleep extension intervention, are discussed.

Weekend sleep extension (catch-up sleep) is associated with lower incidence of coronary calcium score: the ELSA-Brasil study

Weekend sleep extension (catch-up sleep) is associated with lower incidence of coronary calcium score: the ELSA-Brasil study

Beneficial Effects of Photoperiod Lengthening on Sleep Characteristics and Mechanical Hyperalgesia in Injured Rats.

Sleep and muscle injury-related pain are in negative relationship, and sleep extension may be a favorable countermeasure. In response to muscle injury, an adaptive sleep response has been described in rats, characterized by an increase in total sleep time (TST) and nonrapid eye movement (NREM) sleep. This study examined the effects of photoperiod lengthening (a model of sleep prolongation in rats) on the sleep characteristics of muscle-injured rats and whether this lengthening could benefit injury-induced mechanical hyperalgesia using the Von Frey test. Switching from the conventional 12:12 light/dark (LD) photoperiod (light on: 08:00-20:00) to LD 16:8 (light extended to 24:00) gives rats an extra window of sleep. Our results show higher TST and NREM sleep times in LD 16:8 versus LD 12:12 injured rats during 4 h of light lengthening for 7 d postinjury, showing the efficiency of photoperiod lengthening to increase sleep time in injured rats. In addition, a cumulative effect with the adaptive sleep response to muscle injury occurred with higher TST and NREM sleep times in LD 16:8 injured versus noninjured rats during the dark period, reflecting the high need for sleep after the injury. Greater stability and higher relative delta power of NREM sleep during the extended light period were also observed in injured rats. Finally, the extended photoperiod limits the muscle injury-induced mechanical hyperalgesia for 13 d and allows faster recovery of the baseline mechanical threshold. This is associated with reduced pro-inflammatory cytokines levels in the hippocampus, a brain structure involved in pain processing.

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.

Sleep and insulin sensitivity in adolescents at risk of type 2 diabetes: the Sleep Manipulation in Adolescents at Risk of Type 2 Diabetes randomized crossover study.

To investigate the effect of increasing sleep duration for 1 week, compared to a week of habitual and decreased sleep, on insulin sensitivity (IS) in adolescents at risk for type 2 diabetes (T2D). Adolescents, 13-18 years old, at risk for T2D, with obesity and other risk factors, were recruited for a randomized (1:1), open-label, sex-stratified crossover study, that manipulated time-in-bed to modify sleep duration (measured by actigraphy). Following a week of habitual (HB) sleep, time-in-bed was increased (IN) and decreased (DE) by 1 hour 30 min/night for 1 week, counterbalanced across participants (HBINDE or HBDEIN), and separated by a week of washout sleep. The main outcome measure was IS, obtained via 2-hour oral-glucose-tolerance-test conducted after each sleep week. Of the 43 participants recruited, 36 (84%) completed all sleep interventions (52.8% female, age = 15.1 years, body mass index = 99.9th percentile, order: HBINDE = 18 and HBDEIN = 18). On average, during the HB week, participants slept 7 hours 31 min/night; sleep duration was 1 hour 02 min/night higher during the IN week and 1 hour 19 min/night lower during the DE week. We found a significant effect of sleep week on IS with a large effect size. Following the IN sleep week, IS was 20% higher compared to after the HB and DE sleep weeks, but there was no significant difference in IS following HB versus DE sleep weeks. Whenever possible, clinicians should empower youth at risk of T2D to improve their sleep duration, since even a modest increase in sleep duration of 1 h/night for 1 week can have a positive impact on IS in this population. Sleep Extension and IS in Adolescents, https://clinicaltrials.gov/study/NCT03754036, November 23rd, 2018. ClinicalTrials.gov (ID:NCT03754036).

Long-term influence of sleep/wake history on the dynamic neurobehavioural response to sustained sleep restriction.

Chronic sleep restriction, common in today's 24/7 society, causes cumulative neurobehavioural impairment, but the dynamics of the build-up and dissipation of this impairment have not been fully elucidated. We addressed this knowledge gap in a laboratory study involving two, 5-day periods of sleep restriction to 4 hr per day, separated by a 1-day dose-response intervention sleep opportunity. We measured sleep physiological and waking neurobehavioural responses in 70 healthy adults, each randomized to one of seven dose-response intervention sleep doses ranging from 0 to 12 hr, or a non-sleep-restricted control group. As anticipated, sleep physiological markers showed homeostatic dynamics throughout the study, and waking neurobehavioural impairment accumulated across the two sleep restriction periods. Unexpectedly, there was only a slight and short-lived effect of the 1-day dose-response intervention sleep opportunity. Whether the dose-response intervention sleep opportunity involved extension, further restriction or total deprivation of sleep, neurobehavioural functioning during the subsequent second sleep restriction period was dominated by prior sleep-wake history. Our findings revealed a profound and enduring influence of long-term sleep-wake history as a fundamental aspect of the dynamic regulation of the neurobehavioural response to sleep loss.

A feasibility study to understand the components of behavioral sleep extension.

The goal of this study was to examine the contribution of sleep extension intervention components (wearable sleep tracker and coaching) on sleep extension outcomes. This study collected open ended qualitative responses of treatment preference, acceptability, and feasibility as a key outcome. Adults aged 25 to 65 years with sleep duration <7 h and BMI ≥ 25 were randomized into one of four groups: Self-Management (control), Fitbit, Telephone Coaching, or Fitbit + Coaching. Self-report questionnaires and actigraphy were completed at baseline, post-intervention (6 weeks), and 12-weeks. Analyses used mixed models. Among the 38 adults randomized, the Fitbit + Coaching group had larger but non-significant improvements in sleep duration compared with the self-management group. The coaching group demonstrated significant improvements in sleep-related impairment. All groups demonstrated feasibility and acceptability but the Fitbit + Coaching group reported themes of accountability. Results suggest that sleep extension interventions are feasible and acceptable but components affect the pattern of sleep and other outcomes. Sleep extension is feasible and acceptable; the combination of coaching and the wearable device may lead to larger changes in sleep due to enhanced accountability.

The effect of sleep extension on metabolic and androgen parameters of healthy women with habitual short sleep duration: Pilot study

The effect of sleep extension on metabolic and androgen parameters of healthy women with habitual short sleep duration: Pilot study

Effects of a 1-hour per night week-long sleep extension in college students on cardiometabolic parameters, hydration status, and physical activity: A pilot study

ObjectivesShort sleep duration is associated with poor physical health in college students. Few studies examine the effects of sleep extension on physical health in this population, who are susceptible to sleep loss. We examined health effects of a 1-week, 1-hour nightly sleep extension in college students. MethodsTwelve healthy undergraduate college students (83% female; age 20.2 ± 1.5years) completed a study consisting of sleeping typically for 1week (“Habitual”), then extending sleep by ≥1 hour/night during the second week (“Extension”). Sleep and physical activity actigraphy were collected throughout. Following each week, participants completed cardiometabolic assessments including a meal response and provided a urine sample for markers of hydration. ResultsIn Extension compared to Habitual, average sleep duration increased (mean change±SEM, +42.6 ± 15.1 minutes; p = .005), while subjective sleepiness (−1.8 ± 0.8 units; p = .040), systolic blood pressure (−6.6 ± 2.8 mmHg; p = .037), postprandial glucose area under the curve (−26.5 ± 10.2 mg/dL × h; p = .025) and time to baseline (−83.0 ± 46.4 minutes; p = .031) after the meal response, sedentary time (−44.3 ± 15.7 minutes; p = .018), and percentage of wake in moderate-to-vigorous activity (−0.89% ± 0.35%; p = .030) decreased. Participants who increased average sleep duration by ≥20 minutes (n = 9) were better hydrated according to urine osmolality (−187.0 ± 68.4 mOsm/kg; p = .026) and specific gravity (−0.01 ± 0.002 g/mL; p = .012) and had reduced odds of dehydration according to urine osmolality (≥800 mOsm/kg; −67%; OR=0.03; p = .035). ConclusionsThis pilot study's findings suggest that sleep extension may improve cardiometabolic functioning and hydration, and alter sedentary behavior and physical activity, in college students. Sleep extension may be employed to improve multiple aspects of health in this sleep-deprived population.

Predictors for achieving optimal sleep in healthy children: Exploring sleep patterns in a sleep extension trial

Study objectivesEarlier bedtimes can help some children get more sleep, but we don’t know which children, or what features of their usual sleep patterns could predict success with this approach. Using data from a randomized crossover trial of sleep manipulation, we sought to determine this. MethodsParticipants were 99 children aged 8-12years (49.5% female) with no sleep disturbances. Sleep was measured by actigraphy at baseline and over a restriction or extension week (1 hour later or earlier bedtime respectively), randomly allocated and separated by a washout week. Data were compared between baseline (week 1) and extension weeks only (week 3 or 5), using linear or logistic regression analyses as appropriate, controlling for randomization order. ResultsOne hour less total sleep time than average at baseline predicted 29.7 minutes (95% CI: 19.4, 40.1) of sleep gained and 3.45 (95% CI: 1.74, 6.81) times higher odds of successfully extending sleep by >30 minutes. Per standardized variable, less total sleep time and a shorter sleep period time were the strongest predictors (significant odds ratios (ORs) of 2.51 and 2.28, respectively). Later sleep offset, more variability in sleep timing and lower sleep efficiency also predicted sleep gains. The sleep period time cut-point that optimized prediction of successful sleep gains was <8 hours 28 minutes with 75% of children’s baseline sleep in that range. ConclusionsChildren with a baseline sleep period time <8½ hours a night obtained the most sleep from earlier bedtimes maintained over a week, demonstrating experimentally the value of earlier bedtimes to improve sleep. Clinical Trials RegistryAustralian New Zealand Clinical Trial Registry, ACTRN12618001671257, https://www.anzctr.org.au/Trial/Registration/TrialReview.aspx?id=367587&isReview=true.