Understanding Sleep Cycles

What happens when we are asleep?

Most people do not give much thought to what happens when they are asleep. They go to bed, fall asleep and then wake up in the morning refreshed and ready for the new day. If they are lucky they can remember having a dream, and that’s about as far as sleep goes for a lot of people.

What most people do not realize is that a night’s sleep consists of several different phases. Now some people may say at this point, “Who cares how we sleep, get onto the lucid dreaming bit” but surprisingly it can be very beneficial to have knowledge of sleep processes as this will, in the long run aid with your efforts to have a lucid dream. Any knowledge acquired will filter down into your subconscious and over time will assist you.

Sleep patterns

When we sleep, we experience several distinct phases of sleep. One of these phases is the REM (Rapid Eye Movement) phase. It is so called because when you enter the REM phase, a noticeable rapid movement of the eyes can be observed by an onlooker. This is believed to be when we do all of our dreaming.

The chart below shows the different phases of sleep as recorded by an electroencephalogram (EEG) of a subject’s brain activity.

Sleep Cycles - Dream Sleep

As you can see, the REM phase which is at stage 5 of sleep exhibits similar EEG recordings to that of wakefulness.

Interestingly when taking these measurements, other factors like facial muscle tone have to be taken into consideration to differentiate between when a person is in REM or if they are wide awake.

Stage 1 is a transition stage between drowsiness and light sleep. Often a sleeper will see slight hypnagogic imagery. These are like mini-dreams that only last for a fleeting moment. You may have experienced these when falling asleep. You will normally pass quickly to Stage 2.

Stage 2 is what we would term as normal sleep. Here the brainwave patterns show characteristic “spindles” and “K-Complexes”. There is often very little mental activity in this stage.

Stage 3 After about half an hour, you sink into what is termed as “delta sleep”. As you can see from the chart, you will produce large slow brain waves that are characteristic of this quiet sleep phase. You will gradually move into Stage 4 sleep which is a deeper delta state.

After thirty or forty minutes of Stage 4 you will come back to Stage 2 sleep until after approximately ninety minutes after sleep onset, you will enter Stage 5 which is the REM phase. After staying in the REM phase for ten minutes, you re-enter Stage 2 sleep and maybe Stages 3 and 4 until coming up for another REM phase. This pattern repeats for the duration of the night with only one marked difference. As the night progresses, the REM phases become longer and the intervals between the REM phases become shorter. After five or six phases of REM sleep, you will wake up.

As you will see in the next section, the ability to understand when we have REM sleep and are therefore dreaming will help with attaining lucidity in our dreams.