We sometimes hear that we lose weight while sleeping. And that bad sleep contributes to weight gain. True or false ? We take stock with Dr Joëlle Adrien, neurobiologist and president of the National Institute of Sleep and Vigilance.
“A person had written to me saying that she had been trying to lose weight for years. She had heard my advice on the radio, she slept more and she lost weight” remembers Dr Joëlle Adrien, neurobiologist and president of the National Institute of Sleep and Vigilance (INSV). So does sleeping really make you lose weight? “It’s an extrapolation” she answers. Before explaining: “The scientific evidence that we have is that by depriving someone of sleep, they will gain weight.” As a result, some have concluded that by sleeping again, you can lose weight. But to date, no study has confirmed this assumption.
“When you sleep, you secrete a hormone that prevents you from being hungry”
Nevertheless, sleep and weight are physiologically linked. “During sleep, we secrete a hormone that induces satiety and therefore prevents being hungry, it’s leptin. Leptin activates the metabolism, that is to say that we metabolize the food ingested better, so that we store less fat” continues the sleep specialist. If we store less, we grow less. We do not necessarily lose weight, but we gain less weight.
Why do we gain weight if we don’t sleep enough?
“The scientific evidence of weight gain linked to a lack of sleep was provided in the years 1999-2000” reminds Dr. Adrian. “For 15 days, two groups of volunteers, some of whom slept 8 hours and the other 4 hours, were monitored. On arrival, those who slept the least had gained weight and especially fat.” The scientists then concluded that:
- not getting enough sleep decreases glucose metabolism therefore increases storage.
- lack of sleep increases cravings for sugary and fatty foods.
- the less we sleep, the more we are awake, the more time we have to eat.
“Not respecting your sleep needs makes you fat”
What is your natural sleep pattern? What are your needs ? “Not respecting your sleep needs makes you fat. Yet very few people respect them” observes Dr. Adrian. And we don’t all have the same needs. “There are people who are early risers/early goers, others late risers/go to bed late, it’s genetic, you can’t change it but you have to observe yourself to know it” explains the doctor. “We recommend that people, outside of time constraints, for example on vacation, watch what time they fall asleep and what time they wake up to find out their natural sleep pattern.” Once the sleep rhythm is identified, you have to think about:
- have regular sleep schedules: you can shift by one hour on weekends but no sleep in until noon!
- put on light as soon as you wake up: open the curtains, the shutters, turn on the light if necessary…
- doing physical activity in the morning: “A one-hour walk after waking up is very good” advises the specialist.
- do not drink stimulants after 4 p.m. (coffee, tea, alcohol, tobacco, etc.).
- do not overeat in the evening.
- do not force yourself to go back to sleep in the morning, even if you wake up very early.
- take a nap (see below)
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