Missing out on sleep can make saying no to fatty treats even more difficult, new US research has found.
In a Harvard University preliminary study of 12 healthy adults aged 19 to 45, sleep-deprived participants were shown images of low- or high-kilojoule foods over a four-minute period while image scans of their brains were taken.
The photographs, which would change every few seconds, included foods that were healthy (salads, fresh fish and fruit) and unhealthy (strawberry cheesecake, chips and cheeseburgers). As a control, participants were also shown shots of trees, rocks and flowers.
Volunteers also completed questionnaires about how drowsy they were during the day as well as their food likes and dislikes.
And the findings?
"The sleepier you are, the less the prefrontal cortex — the inhibitory area of the brain — is activated when it's shown high-calorie foods," assistant professor of psychology Dr William Killgore told MSNBC.
Which means, that after a late night "you might not have the ability to say no to that extra cookie or dessert," Dr Killgore said.
In the study, patients weren't chronically sleep deprived, but just missed out on an extra hour or two of sleep. Even this was strongly correlated with less activation in the inhibitory areas of the brain when shown rich, fatty foods.
"Even subtle changes in sleep could be having larger effects in ways we hadn't considered, such as appetite, body weight, and food choices," Dr Killgore said.
"It's entirely plausible that with less inhibitory control, you reach for less optimal foods, and this may lead to a lot more weight over a lifetime."
The study was presented at the 2011 meeting of the Associated Professional Sleep Societies in Minneapolis on Monday.
