- Sleep Stages
- Daily cycles of wakefulness and sleep follow a circadian rhythm, within the sleep portion, a cycle called an ultradian rhythm exists.
- These are the five stages of sleep; the first four are called NREM sleep and the last is REM.
- One sleep cycle goes through all 5 stages and lasts 90 minutes.
- Stages 1 and 2 are light sleep; characterised by a change in the electrical activity of the brain.
- The awake brain produces a pattern called a beta wave.
- As you are more relaxed the brain waves become slower and more regular and have a greater amplitude. This is an alpha wave.
- As you go to sleep they slow down further which is a theta wave.
- Stages 3 and 4 are characterised by even slower delta waves. These are called SWS.
- In SWS, most of the bodys physiological repair work happens and biochemical processes take place such as production of growth hormones.
- Each sleep cycle is about 60 minutes in early infancy, increasing to 90 minutes during adolescence.
- Basic Rest-Activity Cycle
- The 90 minute cycle is located within a 24 hour circadian cycle, would make sense to find this 90 minute clock was ticking throughout the day.
- It is called the basic rest activity cycle.
- Eating and drinking behaviour in a group of psychiatric patients over 6 hours was observed.
- Monthly Cycles
- Female menstrual cycle is an obvious infradian rhyth,s
- Fucntion of the menstrual cycle is to regulate ovulation.
- Pituitary gland releases FSH…