Biological rhythm = Any change in a biological activity that repeats peiodiclaly, e.g, daily, monthly, annually
-> Ultradian - less than 24 hours
-> Circadian - 24 hrs
-> Infradian - 24 hrs+
-> Circannual - yearly
E.G: alertness during day
Friedman and Fisher (1967)
People spend time in luxorious isonalation without any time cues whatsoever.
They found rhythm in oral behaviour - waxed and waned every 85-100 minutes
Under stress, the cycle tends to shorten, accounting for the fact that when we get stressed we gain weight
Childrens cycles are shorter than adults. Therefore, they are able to be attentive for 35 minutes and are then restless for 35 minutes
Attentiveness is approximately a 90 minute cycle
We dream during our sleep approx every 90 minutes. We have rhythms of daydreaming during the daytime.
E.G: menstrual cycle
It occurs as a result of seasonal changes.
There's a controversial argument that states the menstrual cycle is related to a womans mood.
This occurs 4-5 days before menses (bleeding) 60% of women experience mild irritation, depression or headaches