Ultradian and Infradian Rhythms

ULTRADIAN RHYTHMS 

SLEEP STAGES & BRAC CYCLE

AO1

• Duration of less than a day
• One example being sleep stages
  • Stage one and two; Light sleep, Beta-Alpha-Theta waves ( waves begin to slow down)
  • Stages two and three; Slow wave sleep, delta waves (repair work occours here and growth hormones generally released)
  • Stage five; Paradoxical sleep (Brain and eyes active, body paralysed) 
• First four stages are Non-Rapid Eye Movement sleep, final stage is Rapid Eye Movement sleep.
• Each cycle is roughly 90 minutes
• Located within the Basic Rest-Activity Cycle (Circadian rhythm)
• FRIEDMAN AND FISHER - noted clear 90 minute cycle in eating and drinking behaviour (Can be argued that as used paitents from a psychiatric unit, they were observing a certain personality type, ergo can we generalise?)

AO2

• General assumption that REM = dreaming
• DEMENT & KLEITMAN proved that sleepers woken when displaying REM brain waves weren't always dreaming. Also that dreaming occours outside REM sleep
• HOBSON & McCARLEY suggest that dreams are psychological read-out  of random electrical signals, typical of REM sleep
• This is, however, based on the assumption that REM activity always equates to dreaming.
• BRAC cycle important as it ensures biological processes work in unison 

INFRADIAN RHYTHMS

MENSTRUAL CYCLE

AO1 POINTS

• Driven by fluctuating hormone levels
• Function is to regulate ovulation 
• PITUITARY…