What Happens To Your Body During 8 Hours Of Sleep?

4 Min Read | By Chris Clark

Last Modified 19 August 2021   First Added 24 July 2016

This article was written and reviewed in line with our editorial policy.

We are regularly told we all need 8 hours of sleep every night. Unfortunately this is rarely achieved, so we have looked at exactly why 8 hours is the recommended amount of sleep we should all be getting. By examining what happens at every stage of the sleep cycle, we explore the ins and outs of how our body and brain get through the night. We look at how 8 hours of sleep helps us to recover from the exercise of the day before and get ready for a new day, fully refreshed and ready to tackle any new challenge.

What Happens to An Athlete’s Body During 8 Hours of Sleep? – Transcript

We are told that 8 hours’ sleep is what we should all aim to get every night, but why? Here we look at exactly what happens to your body through the night and how athletes benefit from a good night sleep.

Stage 1 (Lasts 1-7 minutes, 5% of the night)

–          Between being awake and falling asleep

–          Light sleep

Stage 2 (Lasts 10-25 minutes, 45% of the night)

–          Onset of sleep

–          Becoming disengaged from surroundings

–          Breathing and heart rate are regular

–          Body temperature drops (so sleeping in a cool room is helpful)

Stage 3 (Lasts 20-40 minutes, 25% of the night)

–          Deepest and most restorative sleep

–          Blood pressure drops

–          Breathing becomes slower

–          Muscles are relaxed

–          Blood supply to muscles increases

–          Tissue growth and repair occurs

–          Energy is restored

–          Hormones are released, such as: Growth hormone, essential for growth and development, including muscle development

Stage 4 ‘REM’ – (Lasts 10-60 minutes, 25% of the night)

REM Sleep (25% of night): First occurs about 90 minutes after falling asleep and recurs about every 90 minutes, getting longer later in the night

–          Provides energy to brain and body

–          Supports daytime performance

–          Brain is active and dreams occur

–          Eyes dart back and forth

–          Body becomes immobile and relaxed, as muscles are turned off

How Does The Body Heal Itself Through Each Stage?

Stage 1

The first stage of sleep is when you are beginning to drift off. Your eyelids are heavy and your head starts to drop. Since you are only drowsy, you may be awoken easily and your brain is quite active. As the sleep cycle repeats during the night, you re-enter this drowsy half-awake, half-asleep stage.

Athletes: Brain activity in stage 1 show a series of tightly packed brain wave patterns associated with muscle memory and ‘logging’ movements learned during the day.

Stage 2

After a few minutes, your brain activity slows further, and you descend into light sleep. By the time you are in the second phase of sleep, your eyes stop moving, but you are still woken easily.

Athletes: Your body is preparing for a deep sleep in the next stage, it relaxes and starts to produce HGH – the Human Growth hormone. HGH increases the growth of muscle tissue and regulates the body’s metabolism.

Stage 3

As you start to enter this stage, your sleep spindles stop, showing that your brain has entered moderate sleep. This is followed by deep sleep. As you progress through stage-three sleep, you become difficult to wake.

Athletes: HGH floods the body during deep sleep, helping the recovery process and re-energizing muscles. HGH combines with the activation of the parasympathetic nervous system to support your immune system function and metabolism throughout the day. The hormones Prolactin is released during deep sleep and has anti-inflammatory properties which are thought to be important for recovery of joints.

Stage 4 ‘REM’

After deep sleep, your brain starts to perk up. Most dreams happen here. Your muscles are temporarily paralysed, and your eyes dart back and forth, giving this stage its name, rapid eye movement (REM) sleep.

Athletes: During sleep, extra oxygen is supplied to the muscles and this assists in the breakdown of lactic acid. When you aren’t getting enough sleep, lactic acid builds up in the muscles causing knotted “trigger points” to form. During sleep your body also heals any minor tears which occur in the muscles during the day. Without adequate sleep, you get behind in your healing, and problems build up.

Sleep Cycles

Your body makes an incredible journey through the night as it progresses through each stage, the graph below shows how the body makes the most of a good night sleep.

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