The state of REM is one of the most important stages of sleep, needed by the body to consolidate memories, regulate emotions and solve problems, one of the reasons that you dream.
Couples had less fragmented and longer undisturbed REM periods when sleeping together than when they slept alone, the study found.
Co-sleeping couples also synchronize their sleep patterns, the study found, which researchers think is a sign of relationship satisfaction and depth.
In fact, the higher the participants rated the significance of their relationship to their life, the stronger the sleep synchronization was with their partner, according to the study.
Your body cycles through four distinct phases of sleep to fully restore itself.
In stage one, you start to lightly sleep. You become disengaged from your environment in stage two, where you will spend most of your total sleep time.
Stages three and four contain the deepest, most restorative sleep and the dreamy state of REM, or rapid eye movement sleep.
The REM stage can occur at any time during that period, but on average, it starts about 90 minutes after you’ve fallen asleep. This is when your body and brain are busy storing memories, regulating mood and learning.
It’s also when you dream. Your arm and leg muscles are temporarily paralyzed during REM sleep, so you can’t act out your dreams and injure yourself.
Because a good night’s sleep gives your sleep cycle time to repeat, you’ll go through several REM cycles, which take up about 25% of your total sleeping time.
Another important stage of sleep is deep sleep, when your brain waves slow into what is called delta waves or slow-wave sleep. It’s the time when memories are further processed, muscles are repaired, the immune system is restored and the brain makes new neurons.
A small study
The analysis used dual simultaneous polysomnography, a “very exact, detailed and comprehensive method to capture sleep on many levels — from brain waves to movements, respiration, muscle tension, movements, heart activity,” said Dr. Henning Johannes Drews, a doctor of medicine at the Center for Integrative Psychiatry, Christian-Albrechts-Universität in Kiel, Germany.
Couples who slept together had increased limb movement, but it didn’t appear to affect the brain’s quality of sleep, the study found.
“One could say that while your body is a bit unrulier when sleeping with somebody, your brain is not,” Drews said.
While the study was small and much more research needs to be done, “sleeping with a partner might actually give you an extra boost regarding your mental health, your memory, and creative problem-solving skills,” he said.