Most people are aware of the two different types of sleep: rapid eye movement (REM) and non-REM. However, what many don’t know is that non-REM sleep actually has four different stages that you pass in and out of through the night. How much time you spend on each of these stages and the stage you wake from can have a big impact on how rested you feel and how much energy you have throughout the day. Here are the five stages of sleep and why they matter.
Stages of Sleep
Stage 1 of non-REM sleep
When you first fall asleep, you enter stage 1 of non-REM sleep. This is characterized by the cessation of muscle movement and the slow movement of the eyes behind the eyelid. This is the “twilight” stage of sleep where you are probably still aware of some of the things going on around you. This is a light stage of sleep and you can usually be woken by noises or other disturbances.
Stage 2 of non-REM sleep
This is the stage where you are actually fully asleep and not aware of your surroundings. During stage 2, the heart rate and breathing regulate, the body temperature goes down, the eye movements either slow or stop completely.
Stage 3 of non-REM sleep
Brain waves slow down in stage 3 with only a few bursts of activity. This is a deep sleep where muscles relax and breathing slows even more. This stage of sleep is difficult to awaken from and you may feel disoriented if an alarm or disturbance pulls you out of it.
Stage 4 of non-REM sleep
Stage 4 is an even deeper sleep where the brain waves further slow and sleepers are very difficult to wake. It’s believed that tissue repair occurs during the stage of sleep and that hormones are also released to help with growth.
Stage 5: REM sleep
The final stage of sleep is REM and this is the cycle where we dream. The eyes move rapidly behind the lids and breathing becomes shallow and rapid. Blood pressure and heart rate also increase during REM sleep and the arms and legs are paralyzed so that sleepers can’t act out their dreams. The purpose of this stage (and of dreams) is thought to stimulate the sections of the brain that are needed for memory and learning and a way for the brain to store and sort information. REM sleep occurs approximately 90 minutes into the sleep cycle.
The length of each cycle changes throughout the night, but the typical sleeper will cycle through the stages several times before waking. For those with sleep disorders such as obstructive sleep apnea, the deeper levels of sleep may not be reached as frequently as is normal because they are constantly being woken. This can lead to the body’s inability to repair damage, few dreams, and increased fatigue upon waking and throughout the day.
If you have symptoms such as brain fog, inability to concentrate, the need for naps, irritability, or lack of focus, it could be due to lack of deep sleep. Think obstructive sleep apnea could be the culprit? Request a screening today to find out!