The two main factors that determine the amount of sleep we need are genetics and age. As we age, the amount of sleep our bodies need changes. By adulthood, most healthy people need 7-9 hours. The younger you are, the more sleep you need. Of course, there are “short sleepers,” but they're pretty rare. One common misconception is that older adults don’t need as much sleep as they did in middle age. While older adults tend to sleep more lightly and may wake earlier in the morning, they still need the same amount of sleep over 24 hours. When you sleep, your body rests, recovers and rebuilds itself through four stages. An average sleep cycle lasts about 90 minutes. Ideally, you need 4-6 cycles of sleep every 24 hours to feel fresh and rested. Here’s what happens in each stage and the rough length of each one:
- NREM Stage 1: This stage of light sleeping lasts 5-10 minutes. During this stage, you’re dozing off as your body and brain activity begin to slow down. If you wake up during this stage you may feel as if you haven’t fallen asleep at all.
- NREM Stage 2: During this stage of light sleeping, your muscles begin to relax as your body temperature drops and your heart rate and breathing slow down. Your eye movement stops and your brain waves slow. This stage accounts for about 45%-50% of your time asleep — the most of any stage.
- NREM Stage 3: This is the “deep sleep” stage. During this stage, your body is repairing itself by regrowing tissue, strengthening your immune system and building bones and muscle. During earlier sleep cycles, this stage could last 20 to 40 minutes and gets increasingly shorter as your sleep cycles progress. As you get older, you spend less time in this stage and more time in lighter stages of sleep.
- REM Sleep Stage 4: The majority of our dreams occur during this stage of sleep. Your brain activity greatly increases and can even match or exceed your usual brain activity when you’re awake. Your muscles enter a state of temporary paralysis, except for your eyes — which move rapidly during this stage — and the muscles you need to breathe. Usually, the first period of REM sleep occurs around 90 minutes into your sleep cycle and lasts about 10 minutes. Each of your later REM stages gets longer the more hours you remain asleep.
Getting enough sleep should absolutely be a priority for your health. It’s not a waste of time to make sure you’re getting the recommended amount of deep sleep each night. In fact, losing precious time in bed can lead to larger health problems. If you feel like you’re having trouble getting enough sleep — or you’re still feeling sleepy after getting enough sleep — talk to a healthcare provider. They can help you get to the root of the issue.
