Effects of Impaired Sleep on Energy Balance (SLOPUS)

• Energy expenditure [ Time Frame: Over the course of 24 hours on day 3 ] [ Designated as safety issue: No ]
  Energy expenditure and substrate oxidation rate will be assessed by 24-hour indirect whole-body calorimetry (respiration chamber) on the basis of measurements of oxygen consumption, carbon dioxide production, and nitrogen excretion in urine.
  
  

• Spontaneous energy intake [ Time Frame: Measured after a maximum of 30 minutes meal time on day 1 and day 4 ] [ Designated as safety issue: No ]
  In an attempt to measure spontaneous energy intake in an experimental context, the participant will be given an ad libitum lunch at noon. The ad libitum meal is a homogenous meal with a macronutrient composition of: 15 E%; fat: 30 E%; carbohydrate: 55 E%.The portion of pasta is larger than the expected participant's intake. The meal will be weighted before and after the lunch and ad libitum energy intake is assessed from the amount of the meal consumed by a food technician.
  
  
• Spontaneous physical activity [ Time Frame: 24 hours for 3 consecutive days ] [ Designated as safety issue: No ]
  Spontaneous physical activity is measured by a wrist worn actigrpahy device during the three days of intervention. Moreover, spontaneous activity in the respiration chamber will be assessed by in-biuld microwave radar detectors
  
  
• Appetite regulating hormones and stress hormones [ Time Frame: Measured every half hour over the course of 4 hours on day 1 and day 4 ] [ Designated as safety issue: No ]
  Hormones are sampled from blood, saliva, and urine.
  
  
• Hunger and desire to eat [ Time Frame: Measured every hour or half hour over the course of 9 hours on day 1 and day 4 ] [ Designated as safety issue: No ]
  Hunger and desire to eat is measured using visual analogue scales before and after a standardized breakfast meal challange and before and after an ad libitum meal.
  
  
• Stress hormone (cortisol) [ Time Frame: Measured at 7 am and 7.30 am on day 1 and day 4 ] [ Designated as safety issue: No ]
  Hormones are sampled saliva.
  
  

The background for this project is that despite considerable knowledge of the mechanisms regulating body weight, the prevalence of obesity has not declined. The individual and environmental factors that play a part in energy balance are still not completely understood, and current methods for loosing and maintaining body weight are generally unsuccessful. Knowledge about what brings about changes in metabolism and lifestyle is lacking.

Reduced sleep duration has been observed in parallel with increases in body weight. Lack of sleep has become a hallmark of modern man, and both children and adults sleep less today than just a few decades ago. Research suggests that both too much and too little sleep can lead to obesity, but correlations between sleep deprivation and other lifestyle-related ailments have also been observed. The reasons for these correlations are far from clear, especially in children and adolescents.

The main purpose of SLOPUS is to investigate the effects of reduced sleep on energy and substrate metabolism, and the relevant hormonal systems involved in the underlying mechanisms. Our hypothesis is that acute sleep deprivation in teenagers leads to increased hunger and desire to eat, increased spontaneous energy intake, decreased spontaneous physical activity, and increased fluctuation in the hormones that control energy metabolism.

The investigators aim to recruit twenty-four healthy, normal weight boys aged 15-19 years with normal sleep pat-terns. The study will be conducted as a randomized, crossover study with two conditions. Each participant will be subjected to short sleep (4 hours) and normal sleep (9 hours), in random order, for three consecutive nights in a respiration chamber. They will stay in the chamber for the 24 hours before the last night. In the respiration chamber energy turnover is measured - both how much energy and also the type of substrate combusted. The chamber is equipped with a bed, toilet, television, computer, and communication. Food and drink can be supplied via an airlock. Measurements in the chamber include volitional activities and sleep duration/quality.

Energy turnover will be measured using a ventilated hood system on the first and last day. Here the participants lie down on a bed with their heads under a transparent canopy for 25-minute intervals during the morning. Blood samples will also be taken during these periods. Meal tests will be served, where we measure the amount of food ingested, and subjects will be given questionnaires about hunger and satiety to fill out. Physical activity and heart rate will be measured throughout the trial.

Thus, the present study is likely to result in a number of new and important findings regarding the impact of impaired sleep on energy balance and it might improve the recommendations for optimal sleep in adolescents.