Mutation in Circadian Clock Gene Linked With Night Eating Syndrome

A latest study ties mutation in a pair of circadian genes to a rare eating disorder called night eating syndrome.

Night time snacking leads to great inconvenience and disrupted sleep.  A team of Salk scientists successfully identified a pair of genes that maintains the normal eating schedules in people.

For their  study they introduced a mutated form of one of the pair in mice. They noticed that there was a drastic shift in the eating patterns of these mice, which led to unusual mealtimes and  unwanted weight gain.

"We really never expected that we would be able to decouple the sleep-wake cycle and the eating cycle, especially with a simple mutation," said senior study author Satchidananda Panda, an associate professor in Salk's Regulatory Biology Laboratory. "It opens up a whole lot of future questions about how these cycles are regulated."­­

Earlier it was seen that people with inherited sleep disorder often carried a specific mutation in a protein called PER2. In humans, there are three PERs that play a crucial role in the daily circadian clock.

In collaboration with a team of Chinese scientists the researchers tested whether mutation in an equivalent region of PER1 produces the same effect as that of PER2. The result was as expected, the scientists noticed that the mice that had a mutated PER1 experienced sleep defects and slept earlier than usual.  They got up earlier with food cravings seeking high-calroy food and subsequently put on weight.

"In the mice without PER1, there was no obvious defect in their sleep-wake cycles," said Panda. "Instead, when we looked at their metabolism, we suddenly saw drastic changes."

The mice with PER1 had lower levels of protein during sleeping period and higher levels during the waking period. 

"For a long time, people discounted night eating syndrome as not real," says Panda. "These results in mice suggest that it could actually be a genetic basis for the syndrome." The researchers haven't yet tested, however, whether any humans with night eating syndrome have mutations in PER1.

The finding was reported in Cell Reports today.