New York: An individual's caloric intake and body weight can deeply influence the time spent in specific sleep stages, says a new study. Researchers from the University of Pennsylvania analysed sleep patterns among 36 healthy adults who experienced two consecutive nights of 10 hours in bed per night at the university hospital. Using polysomnography, the researchers recorded physiological changes that occur during sleep on the second night. Body composition and resting energy expenditure were assessed on the morning following the first night of sleep, while food and drink intake was measured each day. The researchers found that body mass index (BMI), body fat percentage and resting energy expenditure were not significant predictors of sleep stage duration, but that overweight adults exhibited a higher percentage of time spent in the rapid-eye movement (REM) stage of sleep than normal-weight adults. REM is a sleep stage when dreams typically occur characterised by faster heart rate and breathing. The researchers also found that increased protein intake predicted less stage 2 sleep -- the period when a person's heart rate and breathing are relatively normal and his/her body temperature lowers slightly -- and predicted more REM sleep. The study findings will be presented at SLEEP 2016 -- a joint meeting of the American Academy of Sleep Medicine and the Sleep Research Society to be held in Denver, Colorado, from June 11 to 15. "In a culture of increasing pressure to sacrifice sleep to maintain productivity, this research adds to the body of knowledge on how lifestyle behaviours may influence the quality of our sleep" said study lead author Andrea M. Spaeth. A 2013 study from the team found that those with late bedtimes and chronic sleep restriction may be more susceptible to weight gain due to the increased consumption of calories during late-night hours. A 2015 study from the same group found that eating less late at night may help curb the concentration and alertness deficits that accompany sleep deprivation.