Sleep Loss Linked to Weight Gain and Mental Fatigue, New Research Shows

Researchers at Columbia University Vagelos College of Physicians and Surgeons conducted a six‑week trial in which healthy adults reduced their nightly sleep by about 80 minutes. Participants gained an average of one pound, spent more time sitting and less time moving, and showed hormonal changes associated with appetite and metabolism. The findings, published in the International Journal of Obesity, suggest that modest, chronic sleep restriction can contribute to obesity and increase long‑term disease risk.

Experts also note that even when total sleep duration meets guidelines, irregular bedtime timing and misaligned circadian signals can leave people mentally exhausted. The body's internal clocks—including the suprachiasmatic nucleus that synchronises cellular rhythms to light cues—can be disrupted by exposure to artificial light and unpredictable schedules, producing fatigue despite seemingly sufficient sleep.