There’s a new player in the obesity conversation—and it’s made while you sleep.

A recent study published in Cell Research has identified a hormone called raptin, produced by the hypothalamus during sleep, that may help regulate appetite and weight.

Xie, LQ., Hu, B., Lu, RB. et al. Raptin, a sleep-induced hypothalamic hormone, suppresses appetite and obesity. Cell Res 35, 165–185 (2025). https://doi.org/10.1038/s41422-025-01078-8

So, what is raptin?

Raptin is a fragment of a larger protein (RCN2) and gets released during sleep. The brain’s internal clock—specifically the suprachiasmatic nucleus—helps regulate its timing.

Once released, raptin seems to act on the brain and stomach to suppress hunger and slow down digestion.

What makes it clinically interesting?

The researchers found that people who were sleep-deprived had lower raptin levels, and they were hungrier and more prone to weight gain.

On the flip side, participants who followed a structured sleep-restriction therapy (used to treat insomnia) actually had higher levels of raptin and improvements in weight-related symptoms.

The study also connected a specific gene variant to lower raptin levels in patients with Night Eating Syndrome, suggesting that raptin might be disrupted in certain disorders that combine sleep and eating behaviour.

Why does this matter?

Therapies that boost raptin levels or mimic its effects might someday offer another tool in the anti-obesity arsenal.

"Our study identifies raptin as a unique hypothalamic hormone that cooperates with GRM3 to suppress appetite and obesity, thus providing a potential new avenue to treat obesity," the study authors wrote.

But even without a rapatin drug, the message is clear: Good sleep hygiene isn’t just about mood or memory—it’s also about metabolism.