Rapid eye movement (REM) sleep is one of the stages that the brain goes through while sleeping. Specific regions of the brain show high electric activity, yet scientists know very little of the significance of these active neurons. Researchers from Switzerland discovered a link between REM sleep and eating behavior.
A team from the University of Bern and the school's hospital (Inselspital) observed that the same neural circuits are highly active during REM sleep and eating behavior. Their findings have been published in the journal Proceedings of the National Academy of Sciences (PNAS).
Previous research on REM sleep determined which regions of the brain are activated during this phase of sleep. For the first time, scientists discovered that suppressing neuron activity in the lateral hypothalamus results in decreased appetite.
Typically, the stages of sleep are light sleep, deep sleep, then REM sleep. The process repeats itself through the night with the REM stages getting longer and more intense each time.
The last round of REM usually lasts up to an hour, accompanied by vivid dreaming, eye movement, increased heart rate, and high activity in specific brain regions.
REM Sleep and Appetite
One active brain region during REM sleep is the lateral hypothalamus. This region responds to feelings of hunger and sends signals when enough food is consumed.
The lateral hypothalamus is also associated with memory functions and emotions. Behavior such as motivation and addiction are also regulated by this small region in the brain.
Professor Dr. Antoine Adamantidis said that their discovery, 'suggests that REM sleep is necessary to stabilize food intake.' To understand how neural activities during REM sleep impact daily behavior, Dr. Adamantidis, and his team used mice models.
Using a technique called optogenetics, the team used light pulses to turn off or shut down specific, active neurons in the lateral hypothalamic during REM sleep in mice. When they woke up, the researchers observed that their behavior changed - the mice consumed less food than usual.
Lukas Oesch said that they were surprised at 'how strongly and persistently our intervention affected the neural activity in the lateral hypothalamus and the behavior of the mice.' Even after four days of regular sleep, he added, the decreased appetite was still present. The results suggest that neural activity during REM sleep is essential for regulating feeding behavior in mammals.
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Sleep Quality
The results show that a substantial amount of sleep is not the only significant factor for overall health and well-being, but more importantly how sleep quality affects eating behavior too. Adamantidis explained, 'This is of particular relevance in our society where not only sleep quantity decreases but where sleep quality is dramatically affected by shift work, late-night screen exposure or social jet-lag in adolescents.'
Associating brain activity during REM sleep and eating behavior can also help develop new therapies for people with eating disorders, addiction, and mood disorders where motivation is a major problem. Adamantidis expressed how they still have a lot of research to do with their discovery before expanding their data to therapeutical approaches.
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