10/12/25, 4:11 PM Biological rhythms: Ultradian
Biological rhythms: Ultradian
Ultradian
¬ a biological rhythm that occurs more than once in a day, taking less than 24 hours to
complete one cycle. Examples are the sleep cycle
The sleep cycle lasts for around 90 minutes, with 5 stages, each having its own
characteristics such as brain waves and physiological effects.
Types of brain waves
Brain waves are monitored using EEGs, and there are 5 types:
Alpha - wakeful rest, meaning brain is relaxed but active (Stage 1)
Beta - alert and working, involved with conscious thought (REM)
Theta - drowsy (Stage 2)
Delta - sleepy and dreaming (Stage 3 and 4)
Gamma (don't need to know this)
https://app.vaia.com/studyset/17951934/summary/71357449/edit 1/6
, 10/12/25, 4:11 PM Biological rhythms: Ultradian
notice how REM and awake is
mostly the same, and stage 4 is
entirely different
https://app.vaia.com/studyset/17951934/summary/71357449/edit 2/6
Biological rhythms: Ultradian
Ultradian
¬ a biological rhythm that occurs more than once in a day, taking less than 24 hours to
complete one cycle. Examples are the sleep cycle
The sleep cycle lasts for around 90 minutes, with 5 stages, each having its own
characteristics such as brain waves and physiological effects.
Types of brain waves
Brain waves are monitored using EEGs, and there are 5 types:
Alpha - wakeful rest, meaning brain is relaxed but active (Stage 1)
Beta - alert and working, involved with conscious thought (REM)
Theta - drowsy (Stage 2)
Delta - sleepy and dreaming (Stage 3 and 4)
Gamma (don't need to know this)
https://app.vaia.com/studyset/17951934/summary/71357449/edit 1/6
, 10/12/25, 4:11 PM Biological rhythms: Ultradian
notice how REM and awake is
mostly the same, and stage 4 is
entirely different
https://app.vaia.com/studyset/17951934/summary/71357449/edit 2/6
