John asked: As far as restorative sleep, how is REM different from Deep? I typically get 2.5-3 hours of REM and 20 of Deep. Does the ratio of these 2 types of sleep mean anything?
Answer by: Steve Fabregas, Research Scientist @ Zeo
How is REM different from Deep?
REM sleep and Deep sleep are two distinct phases of sleep that are very different from each other. As a matter of fact, in some ways, these two phases of sleep are as different from each other as each is to being awake.
Deep sleep occurs toward the beginning of the night and is associated with mental and physical restoration. Also called “Slow Wave Sleep”, this sleep phase helps us to remember solid facts such as state capitals or phone numbers. Physical restoration also takes place during Deep sleep – this the time when the human body secretes the most Human Growth Hormone, which is important for cell growth and regeneration.
REM sleep occurs at the end of the night and plays an important role in more complex memory processing like emotional memory regulation and associative memory processing. In English, that means REM sleep helps us deal with our emotions, and aids in creativity and the learning of complex tasks. For example, some studies have shown that REM sleep can help people find patterns and short cuts in complex math problems. Dreams may be a by-product or an important facet of these kinds of memory processing.
Since REM sleep occurs mostly at the end of the night, if you don’t leave yourself enough time for sleep, you’re probably going to miss out on some REM sleep.
In the end, both phases are important for the restorative elements of sleep. To get good quality sleep, one needs adequate amounts of both Deep and REM sleep every night.
Does the ratio of these 2 types of sleep mean anything?
The raw ratio of REM sleep to Deep sleep may hold personal meaning, especially on nights when it varies from what you usually experience. But this is a complex question, so breaking it down a bit may help us find a good answer.
First, let’s see how these two sleep phases are regulated, then discuss how much of these phases people generally get at night.
The Regulation of Restorative Sleep
REM sleep in humans is controlled by the circadian rhythm. This is the internal body clock. For most people (who usually sleep at night), this means that we tend to get more REM sleep in the early morning hours. Deep sleep, however, is very dependent on how much sleep we’ve had recently. If you’ve been awake for 40 hours, it’s very likely that you’re going to get much more Deep sleep, right away, than you usually get. If, on the other hand, you take a nap in the evening before going to bed, even a short nap, there’s a chance you’re going to get less Deep sleep than usual.
How Much Restorative Sleep Do People Get?
Well, in general, based on sleep studies conducted in laboratories, 20-25% of a typical night of sleep is spent in REM sleep, while 3-23% of a night is spent in Deep sleep. Lots of things can affect these values, though: gender, how sleep deprived you are, how much sleep you got last night, how much caffeine or alcohol you’ve consumed, many medications, and your own personal physiology can all have an impact on Restorative sleep. Age, particularly, plays a big role in how much Deep sleep we get, and thus the ratio of the sleep phases.
To see how much Restorative sleep people usually get according to their age, check out the Zeo Sleep Wheel.
Steve (ZQ: 100) is our resident Research Scientist, working to help people understand the science behind Zeo, as well as the science of sleep. He is one of the driving forces behind our Sleep Research Center.