Biological Rhythms - The Ultradian Rhythm Flashcards
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Q
Ultradian Rhythms
A
Ultradian rhythms last fewer than 24 hours and can be found in the pattern of human sleep. This cycle alternates between REM (rapid eye movement) and NREM (non-rapid eye movement) sleep and consists of 5 stages. The cycle starts at light sleep, progressing to deep sleep and then REM sleep, where brain waves speed up and dreaming occurs. This repeats itself about every 90 minutes throughout the night, and a person can experience up to 5 full cycles in a night.
A complete sleep cycle goes through the 4 stages of NREM sleep before entering REM sleep (stage 5) and then repeating. Research using EEG has highlighted distinct brain wave patterns during the different stages of sleep.
- Stage 1 and 2 - ‘light sleep’ stages. During these stages, brainwave patterns become slower and more rhythmic, starting with alpha waves and progressing to theta waves.
- Stages 3 and 4 - ‘deep sleep’ or slow wave sleep stages. At this stage, it is difficult to wake someone up. This stage is associated with slower delta waves.
- Stage 5 (REM or dream sleep) - Here the body is paralysed to stop the person acting out their dream, and brain activity resembles that of an awake person.
