Stages of Sleep

Question 1

NREM 1

(6)

Answer 1

• lightest phase of sleep
• somewhat alert and low arousal threshold
• heartbeat and breathing slows down
• muscles relax
• alpha and theta waves
• hypnic jerks can occur (involuntary muscle twitches)

Question 2

NREM 2

(4)

Answer 2

• medium arousal threshold
• heartbeat and breathing continues slowing down
• around 20-25 minutes per cycle and 50% of total sleep
• mostly theta waves

Question 3

NREM 3

(7)

Answer 3

• deep sleep and high arousal threshold
• slower delta waves
• little to no eye or muscle activity
• physiological restoration occurs
• sleep inertia occurs if woken up during this stage
• periods decrease as sleep progresses
• sleep talking/walking

Question 4

REM

(8)

Answer 4

• eyeballs rapidly move beneath closed eyelids
• periods increase as sleep progresses
• beta like waves
• muscle atonia
• psychological restoration
• heartbeat and breathing increase
• easier to wake up than NREM 3
• most dreaming occurs