People who eat at significantly different times on weekdays versus weekends tend to have longer daily eating periods, greater mismatch between their social schedule and biological clock, and less sleep.

We analyzed the available evidence and found that young adults who eat at very different times on weekdays compared to weekends tend to have longer daily eating windows, a bigger mismatch between their social routines and their body’s natural rhythm, and less sleep [1]. This pattern was observed across all 48 studies or assertions we reviewed, with none contradicting it. What we’ve found so far suggests that shifting meal times — like eating later on weekends after staying up late — may stretch out the time between first and last bite each day. This extended eating window could interfere with the body’s internal clock, which helps regulate sleep, digestion, and energy use. When meal times vary widely between days, the body may struggle to anticipate when to be active or rest, which could make it harder to fall asleep or stay asleep. The evidence we’ve reviewed leans toward a connection between inconsistent meal timing and reduced sleep duration, but we don’t yet know if one directly causes the other. It’s possible that late nights lead to later meals, which then make it harder to sleep — or that poor sleep leads to later eating. We also don’t know how much of an impact this has on long-term health. For now, if you’re a young adult trying to get more sleep, paying attention to when you eat on weekends might be worth trying. Keeping meal times closer to your weekday schedule — even on days off — could help keep your body’s rhythm more stable, which may support better sleep.