During the night, our brain is quite often more active whilst we are sleeping, gently causing us to go through five different stages of slumber, the most well know one being REM; otherwise known as Rapid Eye Movement.
What are the stages of sleep?
As stated before, there are five stages of sleep and each one has its own purpose for the body which can be identified through brainwaves and are recorded by electroencephalograms. Before the invention of EEGs, psychologists presumed that the brain was totally unconscious during sleep. However, since the 1920s we have been able to study sleep and the five stages that each of us undergoes every single night.
- Stage one is the beginning of the sleep cycle and is the lightest stage of sleep as it is the transitional period between being awake and asleep. During this stage, the brain produces theta waves which are of high amplitude and last between five to ten minutes. Interestingly, if you were to wake a person during this stage of the sleep cycle they will commonly report that they weren’t actually sleeping.
- During the stage two of sleep, the temperature of your body begins to decrease and the rate in which our hearts beat begins to slow as our body relaxes. This stage lasts approximately twenty minutes as the brain produces bursts of rapid wave activity known as sleep spindles. During this period the muscles of the body may twitch; something that some researchers believe is the brain learning which nerves control what muscles during sleep, especially in babies and children.
- After the sleep spindles are complete, the brain then undergoes the third stage of sleep where Delta waves emerge through a fluctuating period of light sleep and very deep sleep.
- Though there is very little difference between stages three and four, it has been found that stage three is considered as delta sleep wherein less than 50% of the waves are delta waves, whereas stage 4 inhibits waves that are more than 50% delta waves. During these stages of very deep sleep you will often find that it is very difficult to wake a person and if woken, they would do so to much confusion and tiredness. This stage of sleep lasts approximately thirty minutes and is the time where sleepwalking and bedwetting are more likely to occur.
- Stage five of the sleep cycle is the REM stage of sleep and is characterised by movements of the eyes, increased respiration and brain activity. It is also interesting to note that whilst REM occurs, the body’s systems become more active whilst the actual muscles become more relaxed. During this time, voluntary muscles such as arms and legs become paralysed by the brain. Very rarely it is possible to become aware of your sleeping state during this time but you will find that you will not be able to wake or gain control of your body. This is also the period that is associated primarily with dreaming.
What are the sequences of the stages?
It is important to realise that the sleeping stages do not simply occur by the number in which they are defined. For example, sleeping occurs at stage one and progress right up to stage four where we drop back into three and two before entering REM sleep at stage five. After REM sleep we mostly return to stage two and the cycles occur roughly four to five times each night.
Is REM sleep Important?
As you may have already realised, the REM stage is highly important to the sleeping process, and if you work in a creative field, the quality or REM that you receive each night can have an impact on how creative you are the next morning. REM sleep is also associated with memory and is theorised by some experts that the reason for our dreaming occurs as a result of our brains saving, analysing and disregarding what we have learnt and done during the day as well as strengthening memories that we have kept for years, including those from our childhoods.
Is there such a thing as an REM disorder?
Unfortunately so, a person can suffer from a REM sleep behaviour disorder (RBD) wherein the paralysis that normally occurs during the period is incomplete or does not occur at all. This means the person will, therefore, act out the dream in which they are having. Unfortunately, the disorder is characterised by vivid, violent and intense dreams which may incur a person to kick, scream, bite, flail and punch amongst other things. Causes for RBD may be as small as alcohol withdrawal.
If you or someone you know suffers from any of the above conditions, it is best to seek medical help as the condition can also be caused by other factors including Parkinson disease and Lewy body dementia. After being tested it is, therefore, possible to be treated for the condition depending on if it is linked with other diseases and or disorders.