Is Sleep the New Black?

We all know the consequences of too many late nights as we force ourselves out of bed. Parents of young children will be acutely aware of the difference between a tired and grumpy child and one refreshed from a good sleep. Although the popularity of Fitbit type devices has meant some people play close attention to their sleep, it is fair to say that until recently, sleep has been overlooked in public health approaches to healthy lifestyles. Sleep medicine has traditionally focused on sleep disorders (such as insomnia and narcolepsy) and medical conditions. Recognising the importance of sleep as a public health issue has seen the emergence of sleep health. Good sleep health includes not only the duration of sleep but also timing, efficiency, how long it takes to get to sleep, subjective satisfaction, and feeling alert while awake(1). National physical activity guidelines in New Zealand and other countries have recognised these issues and included sleep as part of the puzzle(2) 

The acute impact of inadequate sleep is easy to recognise, but the long-term consequences of chronic sleep loss are far-reaching including an increased risk of obesity, the metabolic syndrome and poor mental health (3).

There is evidence our fast-paced modern lifestyle may have a detrimental impact on our sleep both in terms of quantity and quality (4).

Within our multidisciplinary Kidzzz Sleep Health research group, the diversity of our research highlights the interconnections between sleep and many different aspects of health and wellbeing. For example, our research includes investigations into the academic and cognitive impacts of sleep apnoea, pre-bedtime facilitators and inhibitors to sleep (such as screen time), understanding the link between diet and obesity, and the challenges of obtaining enough sleep with chronic conditions such as diabetes. Importantly we are also trying to find new and improved research tools to best measure sleep objectively in children with less respondent burden.  

One important area of public health interest is the link between inadequate sleep (both duration and quality) and obesity (5). Understanding the mechanisms of how poor sleep is a risk factor for obesity in children is one focus of our research group. Potential mechanisms include; changes to appetite regulatory hormones, later bedtimes leaving more time to eat, daytime fatigue leading to decreased physical activity, and a lower inhibitory control in respect to satiety and food choice. Our new Dream (Daily Rest Eating and Activity Monitoring) study will investigate this in children by restricting and extending their usual sleep and measuring effects on diet, exercise and cognitive performance using novel and child-friendly techniques. Interventions to reduce obesity using nutrition and physical activity can be effective but require many resources, time and commitment. Given our inability to change these behaviours long term, we need to look at alternative options – perhaps targeting improvements in sleep might be just the ticket. At the very least, the numerous beneficial effects of a good night’s sleep make it a behaviour that is easy to promote to parents.

Sleep is not just important for growth and development in young babies and children, but also for teenagers. Physiological changes mean teens feel more awake later into the night and combined with busy social, sport and academic demands many do not achieve adequate sleep. Unfortunately, school start times do not accommodate this change in biology and many teenagers wake up feeling sluggish and spend a lot of time catching up over the weekend. One factor associated with poor sleep is screen and technology use. In the SNAP IT (Measurement of Sleep Nutrition and Activity using Photo Images in Teens) research study we are using automated wearable cameras to provide rich data on the pre-bedtime period. Particularly fascinating is how teenagers switch between using multiple devices (multitasking), which is difficult to measure using questionnaires. Poor sleep may lead to increased food intake but emerging research is also providing evidence for a bidirectional relationship, such as how the timing and composition of meals and snacks may influence sleep. 

I am relatively new to the area of sleep research but have found many crossovers and challenges similar to that of nutrition research. Sleep requirements vary at the individual level, for example, six hours may be enough for some but a disaster for others. Sleep requirements and patterns change greatly across the lifespan, especially within childhood. In a similar way to food choice sleep is influenced by environmental and cultural factors but is also regulated within our body by physiological processes and circadian rhythms. The complex interplay between environmental and individual factors make it a truly multidisciplinary field. 

Those researching sleep know that it has always been the new black but it’s time for others promoting a healthy lifestyle to wake up to sleep! There is much to learn and many research questions to answer.  

This article was written by Claire Smith on behalf of the Kidzzz Sleep Health Research Group (Department of Women’s and Children’s Health, Department of Medicine, Dunedin School of Medicine, University of Otago, Department of Human Nutrition, University of Otago) September 2018

References 

1.Buysse DJ. Sleep health: can we define it? Does it matter? Sleep. 2014;37(1):9-17. 

2.Ministry of Health. Sit less, move more, sleep well. Wellington: Ministry of Health; 2017. 

3.Shochat T, Cohen-Zion M, Tzischinsky O. Functional consequences of inadequate sleep in adolescents: a systematic review. Sleep Med Revs. 2014;18(1):75-87. 

4.Matricciani L, Bin YS, Lallukka T, Kronholm E, Dumuid D, Paquet C, et al. Past, present, and future: trends in sleep duration and implications for public health. Sleep Health. 2017;3(5):317-323. 

5.Fatima Y, Doi SA, Mamun AA. Longitudinal impact of sleep on overweight and obesity in children and adolescents: a systematic review and bias-adjusted meta-analysis. Obes Revs. 2015;16(2):137-149.