Functions of Sleep (OCR GCSE Psychology): Revision Note

Why we sleep

• Sleep is a universal and instinctive behaviour — everyone needs it, and we cannot stop ourselves from sleeping

• This suggests it is an evolved behaviour essential for health, survival, and adaptation

Healthy brain

• Sleep plays a vital role in maintaining a healthy, well-functioning brain:

  • Memory consolidation:

    • During REM sleep, the brain strengthens connections formed during the day and consolidates long-term memories

  • Learning and creativity:

    • Sleep supports problem-solving, decision-making, and making creative links between ideas

  • Clearing toxins:

    • When we sleep, the space between brain cells increases, allowing toxins produced during waking hours to be cleared more efficiently

  • Neuroprotection:

    • Sleep protects newly formed memories and prevents interference from fresh experiences

• Overall, a healthy brain relies on consistent sleep to think clearly, remain focused, and support cognitive functioning

Physical repair

• Sleep is essential for physical restoration and body health

  • Slow-wave sleep (deep sleep) is particularly important for physical recovery

  • The immune system becomes more active, helping to fight bacteria and viruses

  • Deep sleep triggers the release of growth hormones, which repair tissues, heal cells, and support muscle development

  • Sleep also regulates important hormones involved in:

    • hunger and fullness

    • blood sugar levels

    • cardiovascular functioning

• Good sleep helps the body remain strong, healthy, and able to recover from everyday strain

Emotional stability

• Sleep is closely linked to emotional and psychological well-being

  • A good night's sleep helps individuals feel alert, calm, and re-energised

  • Sleep reduces levels of stress hormones (such as cortisol), helping people feel relaxed and resilient

  • Poor sleep can lead to irritability, low mood, difficulty regulating emotions, and a higher risk of mental health problems

• Because the brain processes emotional experiences during sleep, consistent rest supports a stable, balanced mood