How much deep sleep do you get on average?
"What Is Deep Sleep?
Deep sleep, also called slow-wave sleep5, occurs in the third stage of non-rapid eye movement (NREM) sleep. During deep sleep, electrical activity in the brain appears in long, slow waves called delta waves6. These waves have a frequency of 0.5 to 2 Hertz7 and they must make up at least 6 seconds of a 30-second window for that window to count as deep sleep.
Typically you descend into deep sleep within an hour of falling asleep, and experience progressively shorter periods of deep sleep as the night wears on. During this stage, automatic body functions like breathing and heart rate are also very slow and your muscles are relaxed. It can be difficult for someone to wake you up, and waking up out of deep sleep may make you feel mentally foggy for up to an hour.
Why Is Deep Sleep Important?
While all stages of sleep are necessary for good health, deep sleep offers specific physical and mental benefits. During deep sleep, your body releases growth hormone and works to build and repair muscles, bones, and tissue, and immune system functioning. Additionally, slow-wave sleep may be important for regulating glucose metabolism8. Elite athletes value slow-wave sleep as it helps replenish energy stores9.
Throughout the day, you receive information inputs14 that strengthen the synapses, or points of communication15, in the networks of your brain. However, your brain cannot take on information forever without rest.
Researchers suggest that deep sleep plays a role in preparing your synapses for the next day. Put another way, your brain evaluates new memories and then preserves and consolidates16 only the ones that are most relevant to avoid saturating memory pathways. Although this theory is still under investigation, evidence shows that people obtain a higher proportion of deep sleep after learning a new task, and show higher concentrations of slow waves in brain areas related to the task.
The results of this process are evident: after a night of good sleep, you are better prepared to take on new information and adapt to new environments."