Performance of wearable sleep trackers during nocturnal sleep and periods of simulated real-world smartphone use

GOAL AND AIMS

To test sleep/wake transition detection of consumer sleep trackers and research-grade actigraphy during nocturnal sleep and simulated peri-sleep behavior involving minimal movement.

FOCUS TECHNOLOGY

Oura Ring Gen 3, Fitbit Sense, AXTRO Fit 3, Xiaomi Mi Band 7, and ActiGraph GT9X.

REFERENCE TECHNOLOGY

Polysomnography.

SAMPLE

Sixty-three participants (36 female) aged 20-68.

DESIGN

Participants engaged in common peri-sleep behavior (reading news articles, watching videos, and exchanging texts) on a smartphone before and after the sleep period. They were woken up during the night to complete a short questionnaire to simulate responding to an incoming message.

CORE ANALYTICS

Detection and timing accuracy for the sleep onset times and wake times.

ADDITIONAL ANALYTICS AND EXPLORATORY ANALYSES

Discrepancy analysis both including and excluding the peri-sleep activity periods. Epoch-by-epoch analysis of rate and extent of wake misclassification during peri-sleep activity periods.

CORE OUTCOMES

Oura and Fitbit were more accurate at detecting sleep/wake transitions than the actigraph and the lower-priced consumer sleep tracker devices. Detection accuracy was less reliable in participants with lower sleep efficiency.

IMPORTANT ADDITIONAL OUTCOMES

With inclusion of peri-sleep periods, specificity and Kappa improved significantly for Oura and Fitbit, but not ActiGraph. All devices misclassified motionless wake as sleep to some extent, but this was less prevalent for Oura and Fitbit.

CORE CONCLUSIONS

Performance of Oura and Fitbit is robust on nights with suboptimal bedtime routines or minor sleep disturbances. Reduced performance on nights with low sleep efficiency bolsters concerns that these devices are less accurate for fragmented or disturbed sleep.

Sleep habits and weight status in Brazilian children aged 4-6 years of age: the PREDI study

OBJECTIVES

To evaluate the association of sleep habits with the weight status of children aged 4-6 years.

METHODS

Data were obtained from the PREDI Study, a Brazilian birth cohort study. The current study was carried out in the homes of the participants during two follow-ups: 2016/17 and 2018. The participants were submitted to anthropometric assessment and demographic, socioeconomic and sleep data were obtained. The child's sleep habits were self-reported by the mother or caregiver on the day of the visit and included information on the following sleep habits during the past week: bedtime routine, rhythmicity, and separation affect determined with the Sleep Habits Inventory for Preschool Children and the Sleep Habits Inventory. Logistic regression and gamma-log regression analyses were used to examine the association of sleep habits with excess body weight of children in the two follow-ups according to sex.

RESULTS

Of the 217 and 185 children included in 2016/17 and 2018, respectively, 66 (30.6%) and 48 (25.9%) had a BMI >85th percentile at 4-6 years, respectively. The median rhythmicity score was higher in children with excess body weight (p = 0.05). Adjusted analysis showed that rhythmicity was associated with excess body weight of girls at ages 4-5 years (OR = 1.42, 95% CI: 1.09-1.86, p = 0.009) and 6 years (OR = 1.32, 95% CI: 1.06-1.65, p = 0.015), even after adjustment for other important covariates. Additionally, the sleep habit "separation affect" was inversely associated with the child's BMI in boys (β = -0.005, 95% CI: -0.010-0.000, p = 0.037).

CONCLUSIONS

In the present study, rhythmicity problems were associated with increased odds of girls aged 4-6 years having excess body weight. These results are important from a public health perspective since strategies aimed at preventing excess body weight in children need to consider the child's sleep quality as a potential risk factor, especially rhythmicity.

Implementation of a nightly bedtime routine: How quickly do things improve?

BACKGROUND

Institution of a consistent bedtime routine has been demonstrated to improve sleep in young children within two weeks. However, no studies have investigated the rate of this change and when most change occurs. The purpose of this study was to examine the nightly change in infant sleep and maternal perceptions after implementing a bedtime routine.

METHODS

Mothers (n=134) and their infant (8-18 months) were randomly assigned to implementation of a bedtime routine intervention for a two-week period.

RESULTS

Two-level piecewise linear growth models showed that the intervention resulted in the most rapid change in the first three nights of the intervention across sleep outcomes, including sleep onset latency, the frequency and duration of nighttime awakenings, sleep consolidation, and maternal perceptions of bedtime ease, sleep quality, and infant mood. No significant additional improvement in sleep onset latency emerged after these first three nights, whereas small additional improvements occurred for all other outcomes throughout the remainder of the intervention period.

CONCLUSIONS

These results indicate that sleep disturbances in infants and toddlers can be quickly ameliorated within just a few nights after implementation of a consistent bedtime routine, including a bath, massage, and quiet activities. Future research should consider the potential mechanisms behind these relatively fast improvements in sleep, such as reduced household chaos or physiological changes (e.g. core body temperature, cortisol).

[Investigation of dose-dependent association between bedtime routines and sleep outcomes in infants and toddlers]

Objective: To investigate the current bedtime routine among Chinese children less than 3 years of age and explore its dose-dependent association with sleep duration and sleep quality. Method: Healthy full-term born children aged 0-35 months were selected by stratified cluster random sampling method from 8 provinces in China following the "Hospital of Province-City-County" sampling technical route during 2012-2013.Brief Infant Sleep Questionnaire(BISQ) was used to assess sleep conditions of these children.Children's personal and family information was obtained by Shanghai Children's Medical Center Socio-demographic Questionnaire.Both of these questionnaires were filled in by parents. The effects of bedtime routine on children's sleep duration and quality were analyzed by multivariate analysis of variance. Result: The children's average age was(12±10) months(n=1 304), of whom 689 were males (52.8%, 689/1 304). There were 48.5%(632/1 304)of the parents reported that their children had not established regular sleep routines. There was a consistent dose-dependent association between bedtime routine and sleep duration, as well as other indicators for sleep quality (all P<0.05). The more regular the sleep routines, the longer the sleep duration, the earlier the children went to sleep, the shorter the sleep onset latency, the fewer the nighttime wakeup and the shorter the nighttime waking.The nighttime sleep duration was significantly longer for those with a bedtime routine 'every night' than those who 'never' had a bedtime routine (9.5(95%CI: 9.4-9.6)vs. 8.9(95%CI: 8.6-9.3)h, t=3.345, P=0.001). Compared with children who never had bedtime routines, children with regular bedtime routines had fewer night wakeup (1.3(95%CI: 1.2-1.4) vs. 2.4( 95%CI: 2.0-2.9), t=3.182, P=0.001) and shorter night waking duration(16.6(95%CI: 14.6-18.8) vs. 59.2 (95%CI: 47.0-72.7)min, t=6.383, P<0.01). Conclusion: The percentage of children who have established regular bedtime routine is low in China. There is significant dose-dependent association between regular bedtime routine and sleep outcomes, especially sleep quality. The more regular the sleep routines, the better the sleep quality.