Sleep: Stages and theories

Question 1

Sleep

Answer 1

periodic, natural loss of consciousness - as distinct from unconsciousness resulting from a coma, general anesthesia, or
hibernation
○ Perceptual window still slightly open when sleeping - can move around bed without falling off, still have a sense of time, still
process information outside of our conscious awareness

Question 2

Circadian rhythm

Answer 2

our biological clock; regular body rhythms (for example, of temperature & wakefulness) that occur on a 24-hour
cycle
○ Body temperature peaks during the day & begins to drop again as you get closer to sleep
○ Can be altered by age & experience - younger people tend to be “night owls” while older people are often “morning larks”

Question 3

NREM sleep

Answer 3

non-rapid eye movement sleep; encompasses all sleep stages except for REM sleep

Question 4

Beta waves

Answer 4

alert, waking state

Question 5

Alpha waves

Answer 5

relatively slow brain waves of a relaxed, awake state

Question 6

NREM (Stage) 1

Answer 6

■ Very brief & light (easy to wake up)
■ Hallucinations
■ Hypnagogic sensations
■ Brain displays theta waves

Question 7

Hallucinations

Answer 7

false sensory experiences, such as seeing something in the absence of an external visual stimulus

Question 8

Hypnagogic sensations

Answer 8

bizarre experiences, such as jerking or a feeling of falling or floating weightlessly, while transitioning
to sleep (also called hypnic sensations)

Question 9

theta waves

Answer 9

low amplitude, high frequency waves

Question 10

NREM (Stage) 2

Answer 10

■ Lasts around 20 minutes, deeper than NREM 1 (but can still be awakened easily)
■ Presence of sleep spindles - bursts of rapid, rhythmic brain-wave activity associated with memory processing

Question 11

NREM (Stage) 3

Answer 11

Deep sleep - lasts for roughly 30 minutes, but gets shorter as the night goes on through each cycle
■ Delta waves

Question 12

Delta waves

Answer 12

large, slow brain waves associated with deep sleep

Question 13

REM sleep

Answer 13

rapid eye movement; recurring sleep stage during which vivid dreams commonly occur; also known as paradoxical sleep, because muscles are relaxed (except for minor twitches) but other body systems are active (sometimes called R sleep)
○ Motor cortex is active (but the brainstem blocks the signals, making you essentially paralyzed)
○ As the night goes on, we get less NREM 3 (deep sleep) & more REM sleep

Question 14

Suprachiasmatic nucleus (SCN)

Answer 14

pair of cell clusters in the hypothalamus that controls circadian rhythm; in response to
light, the SCN adjusts melatonin production, thus modifying our feelings of sleepiness

Question 15

What are sleep’s functions?

Answer 15

Protects
Restores
Memory
Creative thinking
Growth
Energy