Sleep is a biologically regulated process that occurs in stages, including REM and non-REM sleep. It serves important restorative and learning functions. While sleep patterns change with age, disorders like insomnia, sleep apnea, and REM behavior disorder can impact quality of sleep. Non-drug therapies and controlling stimuli are effective treatments for insomnia, though drugs are commonly used in the short-term. Dreams occur primarily in REM sleep and their purpose may be to rehearse threatening situations.
2. Sleeping and Waking
• 猜猜看?那件事我們大約每天花8個小時,每週56小時,每月224小
時,每年2,688個小時,來從事這項活動?
• 王子望著沈睡中的公主,忍不住地親了公主一下;就在那時侯沈睡一
百年的公主竟醒過來了!
3. What Is Sleep?
• Sleep is biologically regulated
• Circadian rhythms
• Melatonin secretion linked to light-dark cycles
• Some adults report needing 7-9 hours a night
• 70-year-old “Miss M.” gets by on one hour per
night!
4. Sleep Is an Altered State
of Consciousness
• Sleep: Awareness of the outside world is
turned off (mostly)
• So why don’t we fall out of bed?
• EEG: The brain is active in sleep
5. Stages of Sleep
• Sleep is not an “on-off” event
• Sleep stages
• Historically: 5 distinct stages
• Currently: Stages 3 & 4 are now joined
6.
7. REM Sleep
• The sleep cycle reverses after about 90
minutes
• Enter REM (paradoxical) stage
• Most dreaming occurs in REM sleep
• Amount of time spent in REM increases
• Cycle through this pattern around 5 times per
night
8.
9. Infant Sleep Patterns
• Infant mammals show a large percentage of REM sleep
• In human, 50% of sleep in the first 2 weeks of life is REM sleep (premature
infants: up to 80%)
• Human infants can move directly from an awake state to REM sleep, by
about 4 months of age, REM sleep is entered through a period of SWS
• REM sleep of infants is quite active: 可能與腦部神經之刺激與發育有關
11. Pattern of Sleep in Elderly Persons
• 貓空夜未眠!
• A decline of total amount of sleep
• Increase in the number of awakening during a night
• Lack of sleep or insomnia(失眠)
• Dramatic progressive decline is in stage 3 and 4 sleep (by age 90,
stages 3 and 4 has disappeared, causing sleep dissatisfaction)
Young adult Elderly person
13. Sleep Is an Adaptive Behavior
• Sleep serves important biological purposes:
– Restoration
– Circadian rhythms
– Facilitation of learning
14. Restoration and Sleep Deprivation
• Restorative Theory: Sleep allows the body to
rest and repair itself
• The evidence:
– Sleep increases after strenuous physical activity
– Growth hormones secreted in sleep
– Replenishes the brain’s energy stores
– Strengthens the immune system
15. Restoration and Sleep Deprivation
Effects of sleep deprivation:
• Mood problems (e.g., irritability)
• Decrements in cognitive performance (e.g.,
attention and short-term memory lapses)
• May compromise the immune system
• Falling asleep for a few seconds to a minute
(microsleeps) can impair ability to perform
critical tasks (e.g., driving)
17. Nap on refreshment and memory
Refreshment
4 *** *
3 **
Memory
SSS rating
***
2 *
* 5
1.5
1
Increase in Speed (Seq / Trial)
1.0 4
Increase in Word Pair
0 0.5
S2 SWS Wake 3
0.0
Before Nap *** : S2 vs. Wake, p < 0.001
After Nap S2 vs. SWS, p = 0.009
-0.5
** : SWS vs. Wake, p = 0.006 2
-1.0
* -1.5 1
1.0
* * -2.0
0.5 -2.5 0
S2 SWS Wake
Increase in Sleepiness
S2 SWS Wake
0.0
* : S2 vs.Wake, p = 0.005 S2
* : S2 vs.Wake, p = 0.001
-0.5 S2
SWS SWS
Wake Wake
-1.0
-1.5
-2.0
S2 SWS Wake
S2 vs. Wake, p < 0.001
S2
SWS S2 vs. SWS, p = 0.014
Wake SWS vs. Wake, p = 0.002
17
18. Circadian Rhythms
Circadian rhythm theory:
• Many creatures are quiet and inactive during
the night because darkness is the time when
danger is highest
• Reduced risk of exposure to predators
• Humans: Are adapted to sleep at night
because our early ancestors were more at risk
in the dark
19. Facilitation of Learning
Sleep: Strengthens neural connections needed for learning
to occur
• Research shows memory in participants who slept was
greater than those who didn’t (Drosopoulos, Schulze,
Fischer, & Born, 2007)
• REM and slow-wave (stages 3 & 4) important for learning
to take place
• Participants who completed a complex task and later
dreamed about it subsequently performed better on the
task than non-dreaming participants (Wamsley, Tucker,
Payne, Benavides, & Stickgold, 2010)
• Students spend more time in REM during exam periods
33. People Dream while Sleeping
• Dreams: Products of an altered state of
consciousness in which images and fantasies
are confused with reality
34. REM Dreams and Non-REM Dreams
• REM dreams: More likely to be bizarre and
include intense emotions, visual and auditory
hallucinations, and uncritical acceptance of
illogical events
• Non-REM dreams: Relatively dull (e.g., what
sweater should I wear?)
35. REM Dreams and Non-REM Dreams
Explanation:
• Non-REM: General de-activation of many
brain regions
• REM: Brain structures associated with
motivation, emotion, reward, vision are
active; pre-frontal cortex is not
36.
37. What Do Dreams Mean?
Freud: Dreams contain hidden content that represents
unconscious conflicts
• Manifest content: The plot of a dream; the way the dream
is remembered
• Latent content: What a dream symbolizes; the material
that is disguised in a dream to protect the dreams from
confronting direct reality
• No scientific evidence that dreams represent hidden
conflicts or for the special symbolic meaning of dream
images
38. Activation-Synthesis Theory
The theory:
• The brain tries to make sense of random brain
activity that occurs during sleep by synthesizing
the activity with stored memories (Hobson et al.,
2000)
• Emotion centers (limbic system) in the brain are
active, which explains the intense emotions;
frontal cortices are not active, which explains the
uncritical acceptance of illogical events
39. Activation-Synthesis Theory
The critics:
• Dreams are not as chaotic as the activation-
synthesis theory suggests (Domhoff, 2003)
• Often similar to “everyday life” waking
experience
40. Evolved Threat-Rehearsal Theory
• Thought question: Why do people often dream
about threatening events?
• Answer: Perhaps dreams help us prepare to cope
with real waking events.
• Dreams sometimes simulate threatening events
so that people can rehearse strategies for coping
(Revonsuo, 2000)
• Dreams may have adaptive value if rehearsal
helps us survive and reproduce
41. Sleep Disorders
• Insomnia: Difficulty falling or staying asleep[12-
20% adults, female > male, elderly > young]
• Obstructive Sleep Apnea (OSA): Breathing may
stop hundreds of times per night
• Narcolepsy: Sufferers unexpectedly fall asleep
• REM Behavior Disorder: Sufferers act out their
dreams
• Somnambulism: Sleep walking
Students may believe that the brain is “switched off” during sleep. This is not the case. The brain is very active, with some regions (brain stem, occipital lobe during dreaming) more active in sleep than during waking.
Some students may feel that they do not dream. The fact is that everybody dreams. Persons who “don’t dream” are simply failing to recall them.
Many students believe dream images have universal meanings. This is not the case. What’s important is what dream content means to the individual dreamer.
Students may mistakenly believe that it’s dangerous to wake a sleepwalker. This is not the case. The best strategy is to gently awaken the sleepwalker and/or guide the person back to where they were sleeping.