Here’s a finding that will make you reconsider your bedtime: the later you stay awake, the more likely you are to lose sleep, eat more calories and ultimately gain weight. It’s a no win proposition for night owls, who are already prone to certain career and lifestyle choices.

Penn researchers discovered the relationship between late-night bedtimes, eating habits and weight gain in a study that appeared in the July issue of journal SLEEP, an online scientific journal co-published by the American Academy of Sleep Medicine.

Men with sleep loss, they found gained more weight than women, and African Americans were especially vulnerable to the effects of sleep loss.

The study is the first of its kind and ambitious in its scope. All of the research took place in controlled laboratory conditions, with a sample of 225 people between 22-50 years old. The participants could each as much as they wanted, in addition to scheduled meals. They were not allowed to exercise, but could watch television, read or play video games.

The subjects who slept only four hours, between 4 a.m. to 8 a.m. consumed about 550 extra calories. They gained about 2.2 lbs after only five nights.

“Although previous epidemiological studies have suggested an association between short sleep duration and weight gain, we were surprised to observe significant weight gain during an in-laboratory study,” said lead author Andrea Spaeth.

The AASM recognizes that obesity as a disease that requires intervention. Obesity and weight gain are risk factors for obstructive sleep apnea, a common sleep disorder that can damage your health and your quality of life. Common signs of sleep apnea include snoring, choking or gasping for air and daytime fatigue.

If you think you may have sleep apnea, make an appointment with a board-certified sleep physician at an AASM accredited sleep center. Depending on your symptoms, the sleep specialist may order a home sleep apnea test or in-lab sleep study. If the diagnosis is positive, he or she may recommend CPAP therapy combined with weight loss.

Sleep loss can cause all kinds of health problems including weight gain. If getting to sleep or staying asleep is a problem, a sleep medicine physician has the expertise to treat your insomnia.