Sleep is essential to good health. If you don’t get enough good quality sleep, your whole life can suffer. But what actually defines good quality? There are five stages of sleep that you generally go through.
There are two distinct sleep types. Non-Rapid Eye Movement (NREM) sleep is also called quiet sleep. The other one is Rapid Eye Movement (REM) sleep and is also called paradoxical or active sleep. Both are important in terms of good quality of sleep on a nightly basis.
The first stage is regarded as a transition period, where you are half awake and half asleep. This period usually only lasts about 10 minutes, and you can be easily woken during this first stage. You might even deny you were actually asleep during this stage. Still, you lose most of your self-awareness during this initial stage and your brain generates alpha waves.
Stage 2 lasts for about 20 minutes; your brain starts creating sleep spindles, which are bursts of rhythmic brain activity. Your heart rate starts slowing down and your body temperature drops a little. Your muscles start becoming paralyzed, so often times you can’t react to the dreams you have whilst you are asleep. Your brain will create beta waves during this stage.
Stage 3 is the transition between light and deep sleep; your brain produces slow delta waves during this period. It is much harder to wake someone at this level of sleep and if you are woken, you may feel groggy for a few minutes, until you regain your bearings.
Your brain will generate delta waves during the 4th stage; this is a deeper sleep lasting about 30 minutes. This stage is where your mental and physical energy gets replenished. If you don’t get sufficient deep sleep, you won’t feel refreshed when you get up in the morning.
Stage 5 is the REM sleep state, and this is when most of your dreaming happens. Your brain creates theta waves in this sleep state. Your respiration rate increases, as does your brain activity. The reason this stage is also called paradoxical sleep is because some muscles relax more, but your brain and other body parts become more active. Voluntary muscles fall into a paralyzed state.
Your first stage of REM sleep usually happens 90-120 minutes after you fall asleep and your first dream lasts around 10 minutes. Further dreams last a bit longer, and the last one can run for an hour or so. REM sleep is highest during infancy through to early childhood, where you can spend up to 50% of your sleep time in REM sleep. Adults only spend around 20% of their time in this state.
If you get woken whilst in REM sleep, you’ll fall back into REM sleep as soon as you go back to sleep again. REM sleep is essential for the health of your brain for numerous reasons, including the formation of your long-term memories.
Each stage of sleep is vital for different reasons, but they all contribute to your overall health. If you don’t get sufficient sleep in the long term, you will definitely feel the effects.