How does not getting enough sleep change what children eat and do? The DREAM Study

This experimental crossover study aims to determine how mild sleep deprivation might influence eating behaviour and activity patterns in children. As it is not known exactly how much sleep each individual child needs, all children will undergo two experimental sleep conditions. In the sleep restriction week (arm 1), the child will go to bed 1 hour later than they normally do, while maintaining usual wake up time. In the sleep extension week (arm 2), the child will go to bed 1 hour earlier than they normally do, while maintaining usual wake up time. All analyses compare the difference between these two experimental weeks. Because not all children will change sleep by exactly one hour in each condition, we expect that the difference between the two conditions should produce a difference in 'usual' sleep time for each child of 1-2 hours per night. This level of mild sleep deprivation is thought to be common in children. Total study duration is 5 weeks. During week 1, participants wear a waist-worn Actigraph accelerometer 24-hours a day for 7 days to measure sleep, physical activity and sedentary behaviour. During week 2, researchers determine the child's "usual" lights out (night) and lights on (morning) time from the accelerometry and accompanying sleep diary data. Participants are allocated to sleep restriction or sleep extension conditions using a randomised, counterbalanced, cross-over design (during weeks 3 and 5, with a one week washout in between). Trained researchers discuss the new bedtime with the parent(s) and child on day 1 of each experimental week during a home visit. Those randomised to sleep extension will be instructed to go to bed one hour earlier than their usual bed time (determined in week 1) each night for 7 nights, while maintaining the usual wake up time. Those randomised to sleep restriction will be instructed to go to bed one hour later than their usual bed time (determined in week 1) each night for 7 nights, while maintaining the usual wake up time. Naps are not allowed. Changing bed time while maintaining wake time reflects the real world where wake times remain relatively constant in children. We will work with parents and children to determine how best to ensure adherence for each family using a variety of strategies including goal setting, securing motivation, preplanning, problem solving, self monitoring and positive reinforcement. Daily text reminders will also encourage adherence. Children wear the accelerometer 24-hours a day during each experimental week (7 full days and nights) and parents complete an accompanying sleep diary, noting lights off and lights on time each day, and time and reason for accelerometer removal (e.g. shower or swimming). One two days of each experimental week, children also wear a small automated camera during waking hours only. This camera attached to the lapel, is worn facing outwards, and automatically takes a picture of the child's environment.