Ultradian Rhythms

A type of biologial rhythm, wih a frequency of more than one cycle in 24hrs, such as the stages of sleep

• Ultradian rhythm follows pattern of altenating REM and NREM sleep
• Stages 1-4 are NREM
• A complete cycle is stages 1-5
• Repeats every 90 mins
• Eviddence from EEG recording show distinct difference in in brainwave patterns during each stage

Stage 1:

• light sleep
• muscle activity slows - occaisonal twitch

Stage 2:

• Slightly deeper
• Breathing/heart rate slow  and slight decrease in body temp
• Theta waves

Stage 3:

• Deep sleep
• Delta waves

Stage 4:

• Slower still - very deep - difficult to rouse
• Limited muscle activity
• Rhythmic breathing

Stage 5:

• REM
• Body paralysed but brain activity speeds up
• Highly correlated with dreaming
• Jerky eye movements and breathing = rapid