Stages of Sleep
Usually sleepers pass through five stages: 1, 2, 3, 4 and REM (rapid eye movement) sleep. These stages progress cyclically from 1 through REM then begin again with stage 1. A complete sleep cycle takes an average of 90 to 110 minutes. The first sleep cycles each night have relatively short REM sleeps and long periods of deep sleep but later in the night, REM periods lengthen and deep sleep time decreases.
Stage 1 is light sleep where you drift in and out of sleep and can be awakened easily. In this stage, the eyes move slowly and muscle activity slows. During this stage, many people experience sudden muscle contractions preceded by a sensation of falling.
In stage 2, eye movement stops and brain waves become slower with only an occasional burst of rapid brain waves. When a person enters stage 3, extremely slow brain waves called delta waves are interspersed with smaller, faster waves. In stage 4, the brain produces delta waves almost exclusively. Stages 3 and 4 are referred to as deep sleep or delta sleep, and it is very difficult to wake someone from them. In deep sleep, there is no eye movement or muscle activity. This is when some children experience bedwetting, sleepwalking or night terrors. In 2008 the sleep profession in the US eliminated the use of stage 4. Stages 3 and 4 are now considered stage 3.
In the REM stage, breathing becomes more rapid, irregular and shallow, eyes jerk rapidly and limb muscles are temporarily paralyzed. Brain waves during this stage increase to levels experienced when a person is awake. Also, heart rate increases, blood pressure rises, males develop erections and the body loses some of the ability to regulate its temperature. This is the time when most dreams occur, and, if awoken during REM sleep, a person can remember the dreams. Most people experience three to five intervals of REM sleep each night.
Infants spend almost 50% of their time in REM sleep. Adults spend nearly half of sleep time in stage 2, about 20% in REM and the other 30% is divided between the other three stages. Older adults spend progressively less time in REM sleep.
As sleep research is still a relatively young field, scientists did not discover REM sleep until 1953 when new machines were developed to monitor brain activity. Before this discovery it was believed that most brain activity ceased during sleep. Since then, scientists have also disproved the idea that deprivation of REM sleep can lead to insanity and have found that lack of REM sleep can alleviate clinical depression although they do not know why. Recent theories link REM sleep to learning and memory.
|Stage||Frequency (Hz)||Amplitude (micro Volts)||Waveform type|
|3||2-4||100-150||spindle waves and slow waves|
|4||0.5-2||100-200||slow waves and delta waves|
The waveform during REM has low amplitudes and high frequencies, just like the waking state. Early researchers actually called it “paradoxial sleep”.
There are many reasons for sleep patterns to become disturbed, but it is important to remember that your circadian rhythm is natural and inbuilt in us and your body will want to return to this cycle.
An adult needs about 7 hours sleep per 24 hour period but can easily feel rested with as little as 5 hours. If you sleep during the day, this comes out of the sleep required so you may find that losing your afternoon nap may well help increase the length of your night time rest.
Avoid too much mental activity just before going to sleep, as well as alcohol, food and strenuous activity and before going to bed, make up a statement for yourself along the lines of :
‘I am going to sleep now and I have no need for conscious thought until I awake at (X) time. I have dealt with all I need to deal with today and when I start work at 9 I will take care of the day ahead. Should I become aware during the night I will simply drift comfortably and easily back to sleep and awake, fully rested at my specified time.’ Some people find it helpful to write down any worries on a pad so they can reassure their mind that they do not need constant reminders of future situations.
Often the more we fight against something or try not to do something, we get whatever we are focusing on. Therefore, focus positively on a deep restful sleep…. Not on waking up. Expect to achieve your goal and believe that you have the ability to get there. Be comfortable that you may become aware each night, since this is part of the natural rhythm of sleep, accept this and relax. Look for the tunnel, path or bridge that leads back into your state of sleep and allow your mind to drift back there. Some people find recalling a past dream can also lead them back to sleep.
Remember all rest is good, as your body will repair itself regardless of whether your brain is asleep or not and sometimes we are unaware of how long we may have drifted off for. Research shows that many people who believe they suffer insomnia, dream they are awake!
It may be that you have some unexpressed emotion that is disturbing your sleep. Emotions can be very raw at times in our lives and we can ‘box’ them until a place in the future when time has dulled the hurt. If you feel that you have bottled something up from the past, it may be a good idea to find release through therapy to help you let them go
Always bear in mind, ‘if you do what you’ve always done, you will get what you’ve always got’. In order to affect change you need to change something and the only things you can change are your thoughts, your environment and your behaviour.