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.
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！
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!
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
Stages of Sleep• Sleep is not an “on-off” event• Sleep stages• Historically: 5 distinct stages• Currently: Stages 3 & 4 are now joined
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
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
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
Sleep Is an Adaptive Behavior• Sleep serves important biological purposes: – Restoration – Circadian rhythms – Facilitation of learning
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
Restoration and Sleep DeprivationEffects 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)
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 WakeIncrease 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
Circadian RhythmsCircadian 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
Facilitation of LearningSleep: 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
preattentive scanning vs. focal attention (visual discrimination)
People Dream while Sleeping• Dreams: Products of an altered state of consciousness in which images and fantasies are confused with reality
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?)
REM Dreams and Non-REM DreamsExplanation:• 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
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
Activation-Synthesis TheoryThe 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
Activation-Synthesis TheoryThe critics:• Dreams are not as chaotic as the activation- synthesis theory suggests (Domhoff, 2003)• Often similar to “everyday life” waking experience
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
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
Clinical Features of OSA 無法熟睡打鼾 晨醒頭痛 夜間頻尿 注意力不集中 性情改變白天嗜睡