Scientists appear to have traced the irresistible 2am pull of the refrigerator to a “night munchies” gene.
They believe that when the PER1 gene is faulty, the natural mechanism that synchronises sleeping and eating goes awry.
This can lead to “night eating syndrome”, or the inability to avoid feeling hungry at night, which can disrupt sleep and lead to over-eating and weight gain.
The discovery was made by conducting tests on mice with two human genes, PER1 and its partner, PER2, which has previously been linked to sleep disturbances.
When PER2 was defective, the mice dozed off earlier than usual, as expected. But de-activating PER1 meant they wanted to eat when they should have been sleeping.
Dr Satchidananda Panda, from the Salk Institute in La Jolla, California, the lead scientist, said: “For a long time, people discounted night eating syndrome as not real. These results suggest it could actually be a genetic basis for the syndrome.”
When the researchers restricted access to food, offering it to the mice only at normal meal times, they found even those with the faulty PER1 gene maintained a normal weight. Over ten weeks, their weight was no different to that of animals with functioning PER1 genes.
The scientists believe PER1 and PER2 are normally synchronised and turned on and off at the same time, keeping sleep and eating cycles aligned. But a mutation in PER1 can break this link, leading to an urge to eat at night.