One of the downsides of freshman year at college is that you will probably gain some weight. This weight is often called the "freshman 15," but it is actually closer to an additional 5 to 10 pounds.
A new study suggests that one cause for the weight gain may be that college students keep changing their sleep patterns at school. Researchers followed 132 first-year students at Brown University. The students kept daily sleep diaries. After 9 weeks, more than half had gained nearly 6 pounds.
Other studies have shown that being sleep deprived can cause overeating and weight gain, as can getting to bed very late. But researchers in this study identified variability as a factor for predicting weight gain, meaning that the students' bedtimes and waking times changed daily.
College students often have variable class schedules and may sleep late one morning and get up early the next. This changing sleep pattern was more pronounced with boys, whose bedtimes and wake times shifted daily by an average of 2 hours, 37 minutes. This apparently keeps changing their metabolism rates and means that even if the student was getting the same amount of sleep each night, the varying sleep and wake-up times were making the effects of sleep deprivation worse.
The study of freshmen at Brown only suggests that there is a correlation between sleep variability and weight gain. Some students did not gain weight and some lost a few pounds. The study also did not ask the students to report in detail what they ate or how active they were. They were asked whether they ate more or less than the previous day, and whether their exercise routine had changed.
The Brown study found that, while girls than boys gained weight, the boys gained more weight individually. The highest gain for a girl was 11 pounds and, for a boy, 18 pounds.
In general, the girls' sleep was more consistent than the boys', and they tended to go to bed earlier. By contrast, because the boys were less consistent with their sleep schedules, how much they slept day to day fluctuated more.