Ultradian Rhythms
Ultradian rhythms are bodily rhythms that last less than 24 hours. The most obvious ultradian rhythm is the different stages of sleep, existing within the ciradian rhythm of the sleep-wake cycle. Sleep is dived into cycles, each lasting about 90 minutes. During these cycles, we will experience 5 different stages of sleep- the first four being characterized as non-rapid eye movement sleep (NREM), and the last stage being characterized as rapid eye movement sleep (REM).
When human beings are awake, the electrical activity in their brain usually takes the form of fast, erratic brain waves. These waves are known as beta waves. During stage 1 of sleep, the brains electrical activity begins to change, with the brain waves becoming more slow and regular. This demonstrates that the persons mind is beginning to relax, and these waves are known as alpha waves. The presence of alpha waves in the brain can usually be used to indicate that the onset of sleep has occurred, and that the person is no longer awake. As well as a change in electrical activity, the persons core body temperature will also drop and their heart-beat slow down.
As the sleeper goes into Stage 2 of sleep, their brain waves become even slower and a greater amplitude. These are called theta waves. This shows that the brain is becoming increasingly more relaxed. During this stage of sleep, it is common to experience sudden bursts of brain activity: known as K complexes and sleep spindles.
Stages 1 and 2 of sleep are commonly referred to as being as being 'light sleep'. This means that people in these stages of sleep can be easily awoken by external factors such as noise.
Stages 3 and 4 of sleep are characterized by even slower brain waves, known as delta waves. Stages 3 and 4 are often referred to as being slow-wave sleep (SWS)- and sleep during this time is far more deep than in the previous two stages. However, the sleeper has not reached a state of unconsciousness, and can still be woken
When human beings are awake, the electrical activity in their brain usually takes the form of fast, erratic brain waves. These waves are known as beta waves. During stage 1 of sleep, the brains electrical activity begins to change, with the brain waves becoming more slow and regular. This demonstrates that the persons mind is beginning to relax, and these waves are known as alpha waves. The presence of alpha waves in the brain can usually be used to indicate that the onset of sleep has occurred, and that the person is no longer awake. As well as a change in electrical activity, the persons core body temperature will also drop and their heart-beat slow down.
As the sleeper goes into Stage 2 of sleep, their brain waves become even slower and a greater amplitude. These are called theta waves. This shows that the brain is becoming increasingly more relaxed. During this stage of sleep, it is common to experience sudden bursts of brain activity: known as K complexes and sleep spindles.
Stages 1 and 2 of sleep are commonly referred to as being as being 'light sleep'. This means that people in these stages of sleep can be easily awoken by external factors such as noise.
Stages 3 and 4 of sleep are characterized by even slower brain waves, known as delta waves. Stages 3 and 4 are often referred to as being slow-wave sleep (SWS)- and sleep during this time is far more deep than in the previous two stages. However, the sleeper has not reached a state of unconsciousness, and can still be woken