Even Mild Sleep Deprivation May Lead to Weight Gain
A Columbia University study found that chronic, mild sleep deprivation (5-6 hours per night) can cause weight gain and increase sedentary time, even though appetite-regulating hormones do not show the changes seen in severe sleep deprivation.
While many studies on sleep deprivation and obesity have focused on severe restrictions (around four hours per night), such conditions are hard to sustain and rarely reflect everyday life. A new study from Columbia University's Vagelos College of Physicians and Surgeons examines the more common mild sleep deprivation, which affects about 30% of adults.
Led by Professor Marie-Pierre St-Onge, a specialist in nutritional medicine, the research team studied 95 adults who typically slept at least seven hours per night and had cardiovascular and metabolic risks. Participants were asked to delay their bedtime by 90 minutes for six weeks, while for another six weeks they maintained their usual schedule. Sleep duration and physical activity were recorded using wrist-worn monitors.
Results showed that during the sleep-restricted period (a reduction of about 80 minutes), participants' average weight increased by approximately 0.45 kg compared to the normal sleep period. Extrapolated over a year, chronic sleep deprivation could lead to significant weight gain. Additionally, sedentary time increased by an average of 17 minutes per day; among men and postmenopausal women, this rise was nearly 30 minutes per day.
Contrary to findings from severe deprivation studies, levels of leptin—a hormone that suppresses appetite—were actually higher during the sleep restriction phase, suggesting a different mechanism. A previous study involving a subset of these participants (38 women) showed that mild sleep reduction increased insulin resistance, especially in postmenopausal women. Another study indicated that reduced sleep made immune cells more likely to migrate to inflammation sites.
St-Onge notes that even a mild sleep deficit, which many people experience daily, can raise the risk of obesity and related conditions such as type 2 diabetes and heart disease. Further research is needed to understand how much health benefit can be gained by improving sleep duration in chronically sleep-deprived individuals.
