Sleep Cycle

  • Sleep occurs in stages
  • During the night you cycle through 2 stages:  REM and non-REM sleep
  • Parts of your brain are active during sleep
  • Your brain and body acts differently during each sleep phase

The Sleep Cycle

Each sleep cycle is comprised of 5 stages

Stage 1 – Light Sleep (5%)
Muscle activity slows
Can be woken easily

Stage 2 – Deeper Sleep (50%)
Brain waves become slower
Eye movements stop

Stage 3 & 4 – Deepest Sleep (25%)
Difficult to wake
No eye movement or muscle activity
Extremely slow brain waves

REM – Dreaming (20%)
HR/BP increase
Rapid, irregular shallow breathing
Eyes jerk rapidly
Limb muscles temporarily paralysed

1 cycle lasts around 90-110 minutes

REM Sleep

  • The most essential part of sleep for feeling rested and staying healthy
  • The last stage of the sleep cycle – starts about 90 minutes after you fall asleep


  • Brain activity increases which promotes learning
  • The brain exercises important neural connections which are key to mental health and wellbeing 
  • The areas of the brain essential in making and retaining memories are stimulated
  • Dreaming and processing of emotions occurs


REM sleep loss is associated with:

  • Increased inflammatory responses
  • Increased risk of obesity, cardiovascular disease and diabetes
  • Memory problems
  • Low mood and depression

How much sleep should I get?

  • There is no right amount of sleep
  • Everyone is different
  • The recommended amount for adults is 7-9 hours
  • Can vary between 6-10 hours
  • Changes as we get older (4-6 hours)
  • Dependent on level of activity during the day
  • More sleep is needed if deprived in previous days (“sleep debt”)

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