Why do we sleep and dream, and what do the main theories say?
The features and functions of sleep (the stages of sleep, circadian rhythms and the restoration and evolutionary theories) and theories of dreaming, including Freud's psychoanalytic theory and the activation-synthesis theory.
A focused answer to the OCR GCSE Psychology J203 sleep and dreaming topic on the features and functions of sleep, covering the stages of sleep, circadian rhythms, the restoration and evolutionary theories of sleep, and theories of dreaming including Freud's psychoanalytic theory and the activation-synthesis theory.
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What this dot point is asking
OCR wants you to describe the features and functions of sleep (the stages of sleep, circadian rhythms, and the restoration and evolutionary theories of why we sleep) and the main theories of dreaming: Freud's psychoanalytic theory and the activation-synthesis theory.
The features of sleep
During a night we pass through repeating stages of sleep:
- Light sleep (drifting off, easily woken),
- Deep sleep (slow brain waves, hard to wake, important for physical restoration), and
- REM (rapid eye movement) sleep, when the brain is active, the eyes move, and most dreaming occurs.
Sleep is controlled by the body's circadian rhythm, a roughly 24-hour internal "body clock" that regulates the sleep-wake cycle, influenced by light and darkness. Disrupting it (shift work, jet lag) harms sleep, an idea relevant to the contemporary core study Williams et al. (1992) and to sleep disorders.
Theories of why we sleep
- Restoration theory. During sleep the body repairs tissues, removes waste, restores energy and releases growth hormone, while the brain consolidates memories and recovers. This explains tiredness after sleep loss and more (especially deep) sleep after exertion or illness.
- Evolutionary theory. Sleep evolved to keep animals safe (still and hidden) during the dark, when they could not forage safely, and to conserve energy. It explains why different species sleep for very different lengths depending on their lifestyle and predators.
Theories of dreaming
- Freud's psychoanalytic theory. Dreams are the "royal road to the unconscious" and represent wish fulfilment: they let us express hidden desires safely in sleep. Freud distinguished the manifest content (the dream's actual storyline we remember) from the latent content (its hidden, true meaning). Because the real wishes are disturbing, they are disguised through symbols, so a dream must be interpreted. His classic core study, the Wolf Man (Freud, 1918), interpreted a patient's dream this way.
- Activation-synthesis theory. Dreams are the brain's attempt to make sense of random neural activity that occurs during REM sleep. The brain is highly active but receives no real input, so it synthesises the random signals into a story-like dream. On this view dreams have no hidden meaning; they are a by-product of brain activity.
Evaluating the theories
The theories of sleep are complementary: restoration is supported by the effects of sleep loss and extra sleep after exertion, while evolutionary theory explains differences between species; the weakness of each is that it cannot explain everything alone (restoration struggles to explain why some active animals sleep little). For dreaming, Freud's theory is influential but unscientific and hard to test (it relies on subjective interpretation), whereas activation-synthesis is more scientific (linked to measurable REM activity) but may dismiss the personal meaning of dreams too readily. As with much of psychology, the fullest picture probably combines biological and psychological views.
Try this
Q1. In which stage of sleep does most dreaming occur? [1 mark]
- Cue. REM (rapid eye movement) sleep.
Q2. State the function of sleep according to restoration theory. [2 marks]
- Cue. To restore and repair the body and brain (energy, tissue repair, memory consolidation).
Q3. What does activation-synthesis theory say dreams are? [2 marks]
- Cue. The brain making sense of random neural activity during REM sleep, with no hidden meaning.
Exam-style practice questions
Practice questions written in the style of OCR exam questions on this dot point, with worked answer explainers. The year tag is the paper they imitate, not the source.
OCR 20204 marksExplain the restoration theory of why we sleep. (J203/02, Section C Sleep and dreaming)Show worked answer →
A 4-mark Explain item rewards the idea that sleep restores the body and brain.
Restoration theory says the function of sleep is to restore and repair the body and brain after the activity of the day. During sleep, the body repairs tissues, removes waste products, restores energy and releases growth hormone, while the brain consolidates memories and recovers. This is why we feel tired when we are short of sleep and why sleep deprivation harms physical and mental functioning. The theory is supported by evidence that more sleep, and especially deep sleep, follows physical exertion or illness.
Markers reward the idea that sleep restores and repairs the body and brain (energy, tissue repair, memory consolidation) and ideally evidence such as increased sleep after exertion.
OCR 20215 marksExplain Freud's theory of dreaming. (J203/02, Section C Sleep and dreaming)Show worked answer →
A 5-mark Explain item rewards the psychoanalytic idea of dreams as wish fulfilment with manifest and latent content.
Freud's psychoanalytic theory says dreams are the route to the unconscious mind and represent wish fulfilment: they let us express hidden desires (often unacceptable ones) safely while we sleep. He distinguished the manifest content (the actual storyline of the dream we remember) from the latent content (the hidden, true meaning beneath it). Because the real wishes are disturbing, they are disguised through symbols, so a dream must be interpreted to reveal its latent meaning. Freud believed analysing dreams could uncover unconscious conflicts. So dreams are meaningful, disguised expressions of unconscious wishes.
Markers reward the ideas of dreams as wish fulfilment and the unconscious, the manifest versus latent content distinction, and the use of symbols and interpretation.
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Sources & how we know this
- OCR GCSE (9-1) Psychology J203 specification — OCR (2017)