For a college student, pulling an all-nighter is a rite of passage. But watch out for your waistline because a new study shows that sleep deprivation may lead to increased caloric intake.

The study, conducted by Marie-Pierre St-Onge, a research associate at Columbia University’s New York Obesity Research Center, showed that when subjects were exposed to four hours of sleep they consumed significantly more calories the next day in comparison to when they slept nine hours.

For the six-day study, St-Onge had 14 men and 13 women randomly exposed to four and nine hour intervals of sleep. The next day, the subjects were exposed to “”typical meals that one would eat at home”” including items like bagels, turkey sandwiches, cookies, frozen entrees, yogurt and vegetables. The nutritional values of the food they consumed were logged.

The study showed that the average calorie intake of the subjects was nearly 300 calories more on the day after they were subjected to less sleep. Additionally, male subjects’ caloric intake was 263 after less sleep, in comparison to women’s average of 329.

St-Onge said she did not know why women consumed more calories than men, but noticed that fat intake was “”more pronounced in women”” and that her research group is currently looking into the actual foods chosen by the subjects while sleep-deprived to look for further trends.

“”It varied greatly between individuals,”” St-Onge said. “”We can say that ice cream was a favorite.””

She said past research has linked sleep problems with obesity, but her study brings the scientific world one step closer to proving causation.

“”There have been epidemiological studies that have shown a link between sleep and obesity,”” St-Onge said. “”I wanted to see if there was a potential causal effect.””

Tucker Peck, a graduate student in the UA’s doctoral program in clinical psychology, said the hormone ghrelin might be to blame.

“”When you don’t sleep much, your body secretes more ghrelin, and ghrelin makes you want to eat more,”” Peck said. “”Worse yet, grhelin also increases your desire for quick rewards, so you might want to eat more sugar and junk food.””

In addition to ghrelin, Peck said sleep deprivation leads to a decrease in leptin, a hormone that makes you feel full.

“”So when you’re not sleeping, your body has more of the signal saying ‘keep eating’ and less of the signal saying ‘stop eating,'”” Peck said.

Peck, who has been researching sleep since 2004, said that though hormone imbalances are an aspect of sleep deprivation, they are not definitely the root cause of increased calorie intake and it may be a psychological issue.

“”Sleep deprivation can make your energy low and your mood worse. So people might be eating food — especially junk food — in the hopes that the calories and sugar will give them more energy,”” Peck said. “”They might be eating sweets and comfort food as a way of trying to cheer themselves up.””

Whether this study can truly show a causal effect has yet to be determined. But St-Onge offered an explanation as to why a lack of sleep could potentially increase one’s appetite for fatty foods.

“”Studies have shown sleep deprivation increases hormones related to hunger and appetite,”” she said. ””There may also be a cognitive control mechanism impairment.””

Regardless of what causes the extra calorie intake, St-Onge said this type of behavior could lead to serious health issues such as obesity and heart disease.

Peck agreed that these findings may have detrimental long-term effects, but also realized that this news is not the end of the world for students trying to pull an all-nighter in the midst of finals.

“”Pulling an occasional all-nighter probably isn’t going to make you need larger pants,”” Peck said. “”But there’s reason to believe that chronic sleep deprivation might lead to overeating and weight gain.””