With a new brain genetics study of genetically engineered mice, researchers now know better why dreams are likely to be put on ice when the ambient temperature is too high or too low. Answer: It's too busy to save your skin.
Neuroscientists at the University of Bern in Switzerland broke a receptor gene in mice and observed how changes in temperature impacted their sleep status, demonstrating that the brain gave priority to temperature control over dreaming.
When we feel comfortable, our brain is easily propelling you between a calm state and a state described by the movement of our eyes: Rapid Eye Movement Sleep (REM).
Far from being a chill out session, watching your own Netflix series as you sleep can be a real mental workout. Your breathing may increase, your eyes follow imaginary characters, and your limbs twitch as they counteract the urge to move.
There must be a good reason for all these efforts. Hypotheses have generally stated that dreams are our way of mentally processing the events of the day. Given that babies who actively process various newly discovered skills spend half of their sleep in this condition, compared to about a quarter in adults, this seems like a good bet.
But it's also a fairly common experience that only dreams come so lightly if your sleeping space is too hot or too cold.
If & quot; warm-blooded & # 39; Animals as we dream, the temperature control is suppressed. Sweating, shaking, wheezing and flushing are not as effective at maintaining our core temperature after the onset of REM sleep.
"This loss of thermoregulation in REM sleep is one of the most peculiar aspects of sleep, especially as we have it fine ̵
It's a Short Logic Leap to Take Over Our Brain Make a choice – process the events of the day or release them to keep your body from freezing or frying. Because for some reason it just can not do both.
To put this assumption to the test, Schmidt and his team focused on the hypothalamus deep in the brain of laboratory mice, a part of the brain in which both thermoregulation and the generation of non-REM sleep play a role ,
Researchers have shown that melanin-concentrating hormone (MCH) neurons are involved in sleep in the dream state, and researchers created the genes for MCH receptors by either switching them off or forcibly activating them through a process called optogenetics.
When normal old laboratory mice were placed in a temperature-controlled environment, the team found that REM sleep lasts longer when the temperature is pleasantly warm.
In comparison, mice without functioning MCH receptors do not show any change in REM sleep while warming as if their hypothalamus is not sensing the outside temperature.
Switching the MCH system on and off with targeted light also showed that melanin-concentrating hormone neurons are the key to controlling REM across the brain in terms of temperature.
"It shows that the amount and timing of REM sleep are tuned exactly to our immediate environment if we do not need to thermoregulate," says Schmidt.
"It also confirms how closely the dream sleep and the loss of thermoregulation are interlinked."
Fine-tuning body temperature and controlling a large brain are two of the most energy-intensive activities on a mammal's to-do list. So it seems reasonable to believe that these two vital tasks will eventually come into conflict.
Since we can not just get up and move to a better place when we sleep, our bodies must do a prime job of keeping our core at a comfortable temperature.
If the conditions do not require this effort, it seems that our brain uses that energy instead to run an account.
"These new data suggest that the function of REM sleep is to activate important brain functions, especially at times when we do not need to spend energy on thermoregulation to optimize the use of energy resources." says Schmidt.
This study was published in Current Biology [19459005veröffentlicht].