If you or any of your clients like to stay up late and then sleep in, you might want to consider resetting your body clocks. A Northwestern University study, published in the July issue of Obesity, reports that people with night-owl behavior tend to consume more calories, eat more fast food, and drink more sugary sodas than those who practice an early-to-bed and early-to-rise routine.

Researchers followed 52 people, average age 30, divided into “late sleepers” (who stayed up until 3:45 am and slept until 10:45 am) and “normal sleepers” (in bed by 12:30 am and awake by 8:00 am). The late sleepers averaged 248 more calories a day, mostly consumed during dinner (about 8:15 pm) and in the late evening. Eating late was also linked to a higher body mass index (BMI). Late sleepers ate twice as much fast food as normal sleepers, but only half the fruits and vegetables.

The investigators found that late sleepers had shorter sleep duration, later sleep onset and offset, and later mealtimes. They consumed more calories after 8:00 pm, and at dinner they consumed more fast food and full-calorie soda and fewer fruits and vegetables. Higher BMI was correlated with later sleep timing, shorter sleep duration, calorie intake after 8:00 pm and fast-food consumption. Sleep timing was independently correlated with fruit and vegetable intake and with calories consumed after 8:00 pm, but when results were controlled for sleep duration, sleep timing did not predict BMI. After the findings were controlled for sleep timing and duration, BMI was predicted by calories consumed after 8:00 pm.

“Our data demonstrate that the timing of sleep affects dietary behavior and timing of caloric intake. Interestingly, even after controlling for sleep duration and timing, consuming calories in the evening was associated with a higher BMI,” the authors stated.