WASHINGTON — Around this time of year, college freshman may feel their jeans getting a bit tighter. Historically, they blamed late-night burgers and pizza for the dreaded “freshman 15.”
Now, a new study shows that first-year weight gain might also be the result of shorter sleep durations.
Researchers looked at data on 132 Brown University freshman compiled by the school’s Sleep for Science program. Each first-year student in the study kept a sleep diary, and over nine weeks, more than half had gained roughly six pounds.
The research team found that those who gained weight were also scrimping on sleep, getting far less than the 9 hours and 15 minutes per night recommended for teens. These freshman also kept late hours, turning in at 1:30 a.m. on average.
But what really struck the researchers was the variability of sleep, and the inability of so many of these new college kids to maintain a regular sleep schedule.
“This study is one of the first that shows in that age group in particular, that sleep duration variability — a lot of changes in sleep time but also the timing of sleep on a daily basis — has an impact on weight gain,” said psychologist Daniel Lewin, associate director of sleep medicine at the Children’s National Health System.
In short, these college kids are constantly resetting their internal clock.
“Our circadian rhythms are not necessarily all that flexible,” said Lewin. “They don’t adjust quickly.”
And this is not just a problem for college students. There are also indications that disrupted sleep patterns can contribute to weight gain in adults.
“It could affect all ages,” said Dr. Samuel Potolicchio, medical director of the Sleep Center at Sibley Hospital.
He says the sleep-weight connection is thought to be quite strong. For example, the sleep disruption caused by sleep apnea makes it far more difficult for those patients to lose extra pounds.
“The disruption of the circadian rhythm, the lack of sleep for whatever reason — all of this will add up to change their eating habits completely,” Potolicchio said.
The Brown University study also found some gender differences. More girls than boys gained weight, but the boys gained larger amounts.
Body mass and sex hormones may account for some of the difference. But the researchers say the girls had more consistent sleep patterns, especially when it came to hours of sleep per night.
The findings were published in the journal Behavioral Sleep Medicine.
