ultradian rhythms

• ultradian rhythms - rhythms with a duration of less than 24 hours

  they can occur multiple times within 24 hours
• STAGES OF SLEEP - cycle lasting 90 minutes that repeats itself multiple times throughout the night

  STAGE 1-2: lighter sleep where brain waves slowly start to slow down. NREM

  STAGE 3-4: deeper sleep that is difficult to wake someone up. also NREM

  STAGE 5: where dreaming occurs. REM. person is paralysed and brain activity is the same as if the person was awake
• A03

  + supportive study by dement and kleitman - studies 33 participants, controlling their caffeine and alcohol intake. using EEG scans they found discrete patterns of rapid eye movement without fail on the 126 nights they were observed. individuals could also remember their dreams from the night before, which led to the conclusion that REM sleep is associated with dreaming. this therefore shows the distinct differences and patterns in different stages of sleep
• A03 - individual differences

  research has found that there are different durations of time spent in each stage of the sleep cycle. tucker et al found that this varied widely with individuals, specifically in stages 3 and 4 of the sleep cycle (just before REM sleep) where each participant spent a different length of time in this stage. this therefore suggests there are innate individual differences that affect the stages of sleep, therefore meaning general conclusions cannot be established.