Columbia University study links short sleep to weight gain

A six‑week experiment by researchers at Columbia University’s Vagelos College of Physicians and Surgeons found that reducing nightly sleep by about 90 minutes caused measurable weight gain and increased sedentary behavior in healthy adults. Ninety‑five participants who normally slept 7‑8 hours were asked to delay bedtime for six weeks, cutting sleep to roughly 5½‑6½ hours. At the end of the period they weighed on average 0.5 kg (about one pound) more, showed a larger waist circumference, and spent 17 minutes more per day sitting; the increase rose to nearly 30 minutes for men and post‑menopausal women. Hormonal analysis showed higher ghrelin and lower leptin levels, indicating a shift toward greater appetite. The findings, published in *Annals of Internal Medicine*, suggest that even moderate, chronic sleep restriction can raise the risk of obesity, type‑2 diabetes, and heart disease. “The main takeaway is that sustaining a reduction in sleep… leads to weight gain and increases in waist circumference,” said study author Marie‑Pierre St‑Onge. The researchers note that about one‑third of U.S. adults already sleep less than recommended, underscoring the public‑health relevance of adequate nightly rest.