Ultradian rhythms

Question 1

What are ultradian rhythms?

Answer 1

Rhythms lasting fewer than 24 hours, such as the 90-minute sleep cycle alternating between NREM and REM sleep.

Question 2

How many stages are in a complete sleep cycle

Answer 2

five stages: four NREM stages followed by one REM stage

Question 3

How long does a full sleep cycle typically last

Answer 3

About 90 minutes

Question 4

How many sleep cycles can a person experience in one night

Answer 4

Up to five full cycles

Question 5

What happens during Stages 1 and 2 of the sleep cycle?

Answer 5

• Light sleep stages.
• Brainwaves slow and become more rhythmic, transitioning from alpha to theta waves.

Question 6

What characterises Stages 3 and 4 of the sleep cycle?

Answer 6

• Deep sleep or slow-wave sleep.
• Dominated by slow delta waves, making it difficult to wake someone up

Question 7

What is the primary feature of Stage 5 (REM sleep)?

Answer 7

• Brain activity resembles an awake state.
• The body is paralyzed to prevent acting out dreams.

Question 8

What tools are used to study the sleep cycle?

Answer 8

EEG (electroencephalogram), which highlights distinct brainwave patterns during different sleep stages

Question 9

Individual Differences in Sleep Cycles

Answer 9

Tucker et al. (2007)

• Found significant differences between participants in the duration of stages 3 and 4, just before REM sleep.
• Demonstrates innate individual differences in ultradian rhythms, showing the need to focus on these differences in sleep studies.

Question 10

Case Study of Randy Gardener

Answer 10

Randy Gardener remained awake for 264 hours, coping well with sleep loss.

After recovery, he regained 70% of Stage 4 sleep and 50% of REM sleep, highlighting flexibility in ultradian rhythms.