Effects of Time of Sleep Restriction in Obesity

• Appetite regulating hormones and stress hormones [ Time Frame: Measured every hour over the course of 24 hours on day 3 ] [ Designated as safety issue: No ]
  Hormones are sampled from blood
  
  

• Hunger and satiety [ Time Frame: Measured every 4 hour over the course of 12 hours on day 2 and 3 ] [ Designated as safety issue: No ]
  Hunger and saciety are measured using visual analogue scales before and after breakfast, lunch and dinner meal
  
  
• Food intake [ Time Frame: measured each meal ] [ Designated as safety issue: No ]
  The meal will be weighted before and after the breakfast, lunch and dinner. Energy and nutrient intake are assessed from the amount of the meal consumed.
  
  

The reduction of sleep time has now become a common habit, driven by the demands and opportunities of modern society. Some studies have suggested that sleep restriction would be an important factor in predisposing to obesity. However studies of sleep restriction in obese individuals have not yet been conducted. Still, the time of sleep restriction varies greatly between studies, making it difficult to compare results.

The investigators aim to recruit 20 young adults, 10 obese and 10 normal weight individuals. The study will be conducted as a randomized, crossover study with three conditions. Each participant will be subjected to reduction of the beginning of sleep (from 3-7h), reduction of the end of sleep (from 23-3h), and normal sleep (from 23-7h), in random order, for three consecutive nights.

In each condition, subjects will stay for 4 days in the laboratory. Three control meals will be offered. Visual analogue scales will be applied before and after each meal to assess hunger and appetite for different food categories. Blood samples will be collected hourly during 24 hours.