Effects of Impaired Sleep on Energy Balance
Condition: Obesity; Sleep
Study type: Interventional

Summary: 
      The main aim of this study is to examine the effects of restricted sleep on energy and
      substrate metabolism as well as relevant hormonal systems that might be involved in the
      underlying mechanisms.

      The investigators hypothesize that short-term sleep curtailment in adolescents is accompanied
      by 1) increased hunger and desire to eat; 2) increased spontaneous energy intake; 3) reduced
      spontaneous physical activity; and 4) increased fluctuation in hormones in a way that could
      favour a positive energy balance and potentially weight gain on the long run.
    

Detailed description: 
      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.
    

Intervention name(s): Sleep duration
Intervention type(s): Behavioral
Intervention description(s): Duration of sleep per night
Other intervention name(s): Sleep curtailment, acute sleep deprivation
Allocation: Randomized
Intervention model: Crossover Assignment
Masking: None (Open Label)
Primary purpose: Prevention
Keywords: Appetite regulation; Physical activity; Energy balance