The Stages of Sleep

Sleep is essential for your health – it refreshes the mind and repairs the body and we know it plays a very important role in our overall health, well-being and happiness. Sleep is made up of a number of stages, known as stages one, two, three and four and rapid eye movement (REM) sleep.

THE SLEEP CYCLE

Sleep is not only made up of a number of different stages but it also follows cycles, referred to as a sleep cycle. Usually every one-and-a-half to two hours, a new cycle of sleep begins. Each of these cycles includes some REM sleep and brief periods of wakefulness. The first couple of cycles contain relatively short periods of REM sleep and longer periods of deep sleep. As your sleep progresses, you spend more time in REM sleep and less in deep sleep. Interestingly, the first three hours of your sleep are often the deepest.

STAGE ONE

This is your transition point between being awake and asleep. Here you tend to wake easily. Stage one is the dozing and drowsy stage – you continually move between being asleep and awake.

STAGE TWO

This is the stage where you lose awareness of your surroundings, your body temperature starts to drop and your breathing and heart rate slow down.

STAGE THREE

This is the start of the deep sleep stages. Your blood pressure, heart rate and breathing become very slow and your muscles start to relax.

STAGE FOUR

This is a continuation from stage three, as well as your blood pressure, heart rate and breathing slowing down and your muscles relaxing, this is the stage where growth and repair occur.

These four stages are commonly referred to as non-rapid eye movement sleep. NREM is what you experience for the remaining three-quarters of your sleep time.  People awakened during deep sleep do not adjust immediately and often feel disoriented for several minutes after they wake up. This is the stage where some children experience bedwetting or sleepwalking as well.

RAPID EYE MOVEMENT (REM)

Rapid eye movement sleep occurs regularly during sleep, about once every 90 to 120 minutes and makes up about one-quarter of your night’s sleep. Most dreams are thought to occur during REM sleep. In REM sleep, your eyes move rapidly, your blood pressure and heart rate go up, and your brain becomes very active. This stage is very important for learning and creating new memories. When people awaken during REM sleep, this is the time when they often describe having bizarre dreams.

One interesting point is the relationship between body temperature and sleep. People lose some of the ability to regulate their body temperature during REM, so abnormally hot or cold temperatures in your room or sleeping environment can disrupt this stage of sleep. A more interesting point is if your REM sleep is disrupted one night, we often jump straight into REM sleep the next night and go through extended periods of REM until we catch up on this stage of sleep.

Whilst many people would say having an understanding of the different sleep stages is useless, as you’re already asleep anyway, it could be argued it is important to have some form of understanding to illustrate just how these stages affect our health and if we are ignoring or neglecting one particular stage.

(Photo Courtesy of twentyfourhourgym.com)