In healthy adults, approximately 13% to 23% of your sleep is deep sleep (stages 3 and 4 & REM sleep). So if you sleep 8 hours a night, that's about 62 to 110 minutes.
However, as you age, you need less deep sleep.
During deep sleep, multiple functions of the mind and body occur:
- memory is consolidated
- learning and emotional processes
- physical recovery occurs
- Blood sugar levels and metabolic balance
- Immune system is vibrant
- brain detox
Without deep sleep, these functions cannot function and symptoms of sleep deprivation will occur.
How much REM sleep should you get?
While there's no official consensus on how much REM sleep you should get, dreaming is most common during this stage. Experts believe dreaming can help you process your emotions and solidify certain memories.
For most adults, REM takes up about 20 to 25 percent of sleep , which seems healthy in an average sleep cycle. However, sleep studies raise some interesting questions. A recent study suggests that large amounts of REM sleep may be linked to depression. But don't suddenly change your sleeping habits—it's unclear which is the cause and which is the effect.
How much light sleep do you need?
Although sleep scientists agree that light sleep is good for you, there's no minimum to strive for. Light sleep is usually the default stage, and it's almost impossible to avoid it if you're fully asleep.
However, sleeping too much on a regular basis has been linked to an increased risk of obesity, depression, pain, heart disease and even death.
How much sleep does a child need?
Babies and children need more sleep than adults. Babies need it most, sleeping approximately 16 hours out of every 24 hours. They spend about 50% of their sleep in REM, and the other 50% in NREM sleep, which is divided into stages 1 to 4 and cycles between light and deep.
As children get older, the amount of sleep they need will vary:
- Toddler: 11 to 14 hours
- Preschoolers: 10 to 13 hours
- School-age children: 9 to 12 hours
- Teens: 8 to 10 hours
Adequate sleep seems to make people feel restful, so the light, deep and REM ratios are probably exactly what young people should be.
If they have trouble falling asleep, staying asleep, or sleeping well, or if they sleep too much for their age, they may be irritable, may have learning and memory problems, or may be more susceptible to illness.
