Entry for:ASA Peer Prize in Sleep Research
We know that how much adolescents sleep matters a great deal to their wellbeing. This study showed that how variable (or irregular) they sleep from one day to another also matters to their psychological wellbeing.
Published in SLEEP (Dec 2016), this is the first study to:
- Describe how adolescents’ sleep may vary from day to day (i.e., variability) without the constraints of school schedules, and
- Examine how daily sleep variability may be related to adolescents’ mood, beyond the effects of average sleep duration and quality.
Methodology used in this study:
- 146 adolescents from Australian secondary colleges participated in this study. They had an average age of 16.2 years, and 52.7% were female.
- During a 15-day school vacation, participants wore an actigraph, which measured daily sleep objectively.
- They also completed questionnaires on sleep quality and mood (symptoms of depression and anxiety).
- We used advanced statistical modelling to analyse daily sleep data.
Highlights of the findings:
- Adolescents who had more variable sleep duration and time to fall asleep reported their sleep quality to be worse, which in turn, was associated with higher symptoms of depression and anxiety.
- Notably, the association between mood and the variability in time falling asleep was curvilinear: as time to fall asleep became more variable, its mood-worsening effect via perceived sleep quality, accelerated.
- The effects of daily sleep variability in this study were over and above the effects of average sleep duration or quality.
What these findings tell us:
- It is important to consider daily sleep variability in addition to the average sleep duration or quality.
- Without the constraint of school schedules, variable daily sleep is linked to worse perceived sleep quality and mood in adolescents.
- It is possible that promoting more regular and stable sleep patterns may improve both sleep and mood in adolescents.
2. Share a PubMed or DOI link to article
3. Do you have any ideas to expand upon this research? Are you looking for collaborators?
No two nights’ sleep is the same. Sleep across multiple days can be characterized along two dimensions: the mean across the days, and the daily variability around the mean. The latter is currently poorly understood and requires much research efforts going forward.
Over the past couple of years, we have worked towards further our understanding of daily sleep variability, with the goal of promoting the incorporation of variability as a second dimension in sleep research, and moving the field beyond the mean values.
The two pieces of foundational work we have done are:
1 Evidence synthesis. In 2016, we published a systematic review of nearly 4000 unique records, showing that sleep variability matters to a wide range of mental and physical health outcomes. To make it easy to access the findings and continue to add new studies as they come out, we created a website (www.sleepv.org) with an ongoing systematic review, as well as tools for researchers to incorporate variability in their own work.
2 Robust methodology. We developed a robust modelling method for analysing variability. A technical report on the method can be found here. To make this method accessible to researchers, we made a free open source R package that can be accessed via GitHub or CRAN.
By making high quality evidence synthesis and a robust methodology openly available, we hope to see more sleep researchers incorporate variability as a second dimension in their existing work, so the empirical body of work in this area could grow.
We cannot do this on our own. We would be pleased to hear from researchers who are interested in this line of work. If you have recently published relevant work, please let us know so we could add it to our ongoing review. If you are interested in looking at variability in your own work, we would be happy to discuss ideas on collaboration.
Work related to this paper:
- Bei, B., Wiley, J. F., Trinder, J., & Manber, R. (2016). Beyond the mean: A systematic review on the correlates of daily intraindividual variability of sleep/wake patterns. Sleep Medicine Reviews, 28(0), 104–120. Companion website: www.sleepv.org.
- Wiley, J. F., Bei, B., Trinder, J., & Manber, R. (2014). Variability as a Predictor: A Bayesian Variability Model for Small Samples and Few Repeated Measures. arXiv [stat.AP]. http://arxiv.org/abs/1411.2961
- Bei, B., Allen, N. B., Nicholas, C. L., Dudgeon, P., Murray, G., & Trinder, J. (2014). Actigraphy-assessed sleep during school and vacation periods: a naturalistic study of restricted and extended sleep opportunities in adolescents. Journal of Sleep Research, 23(1), 107–117.
- Bei, B., Wiley, J. F., Allen, N. B., & Trinder, J. (2015). A cognitive vulnerability model on sleep and mood in adolescents under naturalistically restricted and extended sleep opportunities. Sleep, 38(3), 453–461.
- Harbard, E., Allen, N. B., Trinder, J., & Bei, B. (2016). What’s Keeping Teenagers Up? Prebedtime behaviors and actigraphy-assessed sleep over school and vacation. The Journal of Adolescent Health, 58(4), 426–432.