As we soon reach the longest day of the year and the sun rises around 6 a.m. in mainland France, a study suggests that have light in your room when you sleep would lead to weight gain in women.
“Turning off the lights when sleeping can be a useful tool in reducing the risk of weight gain and overweight or obesity”, Summarized Dr. Yong-Moon Mark Park, a researcher at the Research Triangle Park of North Carolina (United States), and principal author of the study published on June 10 in the JAMA Internal Medicine.
For this study, Dr. Park’s team relied on self-reported data from nearly 44,000 women aged 35 to 74. It should be noted that they did not work at night, were not pregnant, and did not sleep during the day. By cross-checking the data on weight with those of the night light, the researchers found that women sleeping with a light on were 17% more likely to gain 5 kg or more in five years. The intensity of the light would also be important: “For example, the use of a small nightlight was not associated with weight gain, whereas women who slept with a light or television were exposed to this risk”, Detailed Dr. Park. the scientists specified that this association of nocturnal light and weight remained exact even after taking into account other factors such as diet or physical activity of the participants.
To explain this strange correlation, Dr. Park put forward the hypothesis of a disruption of the sleep-wake cycle due to an effect of light on the secretion of melatonin, the sleep hormone. Other hormonal variations in the body could be disturbed by the presence of light when sleeping, and ultimately disrupt the metabolism. Additionally, keeping a light on at night could lead to shorter nights, which in turn affect food intake and exercise. In short, a vicious circle. As far as possible, it would therefore be better to sleep in complete darkness to ensure sufficiently deep and restful sleep.