- Lasts approximately 15 mintues.
- The EEG levels are characterised by theta waves.
- EOG indicates rolling eye movements.
- EMG shows reductions in muscle tension.
- Heart rate and temperature fall.
- A hypnogogic state may occur, causing hallucinations e.g myclonic jerks.
- The lightest stage of sleep and we are easily awakened.
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- Lasts approximately 20 minutes.
- EEG activity is characterised by larger and slower theta waves and short bursts of high frequency sleep spindles.
- EOG shows little eye movement.
- EMG shows the muscles are relaxed.
- K-complexes also occur; our response to external and internal stimuli.
- It is still easy to be awakened.
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- Lasts approximately 15 minutes.
- EEG activity is characterised by long, slow delta waves with some sleep spindles.
- The EOG and EMG are the same as stage 2.
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- Lasts approximately 30 minutes.
- Also known as slow wave sleep (SWS) because of the long, slow delta waves of the EEG.
- This is deep sleep so it is hard to wake someone from.
- Body temperature, heart rate and blood pressure drops to their lowest point.
- Growth hormones are secreted.
- The stage when parasomnias, such as sleep-walking and night terrors occur.
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Stage 5 (REM)
- Lasts approximately 10 minutes in the 1st cycle and builds up to an hour by the 4th and 5th cycles.
- EEG activity is characterised by beta waves, which also occur during a relaxed waking state.
- This high level of brain activity is linked to dreaming.
- Also been called paradoxical sleep because of the EEG readings show that the brain is very active, whilst the EMG readings show that the body is paralysed.
- It is the hardest sleep to wake someone from, as the paralysis prevents us from acting out our dreams.
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