Chapter 10

Question 1

what are the three biological clocks?

Answer 1

1. circadian rhythms (24 hours): key for regulation of sleep cycles; enable us to anticipate an event before that event
2. ultradian rhythms repeat more than once a day
3. infradian rhythms repeat less frequently than once a day

Question 2

what are biological clocks?

Answer 2

internal clocks that guide timing of behavior and biological processes
- every animal has own endogenous clock
- rest by light or other physical cues

Question 3

what is zeitgeber?

Answer 3

any cue an animal uses to synchronize its activity with the environment

Question 4

what is a free-running biological clock

Answer 4

rhythm of behavior shown by animal deprived of external cues about time of day
- results in animal’s behavior governed by biological clock (most time is longer than 24 hrs)

Question 5

where is the biological clock located?

Answer 5

located in suprachiasmatic nucleus (SCN) in hypothalamus above optic chiasm
- lesions of SCN eliminate circadian rhythms of drinking, locomotion, and hormone secretion
- isolated SCN cells continue to show circadian rhythm for days or weeks

Question 6

what is the retinohypothalamic pathway?

Answer 6

light-dark cycles set the biological clock
- biological clock reset by light and SCN stimulated by light
- light information from eye reaches SCN directly via retinohypothalamic pathway

Question 7

what is the retinohypothalamic pathway made of?

Answer 7

specialized ganglion cells directly transmit light information from eye to SCN
- these cells are sensitive to light and contain melanopsin

Question 8

what does melatonin do?

Answer 8

SCN informs pineal gland when it’s dark
- pineal gland secrete melatonin (key for promoting sleep)
- blind individual must take melatonin
- bight light reduce melatonin production while darkness increase melatonin production

Question 9

how does our circadian rhythm change?

Answer 9

at puberty, it shift so get up later in day
- as we get older, we. get up earlier

Question 10

what is used to determine what stage of sleep someone is in?

Answer 10

EEG activity is used to determine what stage of sleep a person is in

Question 11

what is the brain activity in normal and just before sleep?

Answer 11

normal waking state: characterized by presence of beta wave
just before sleep (drowsiness): alpha waves increase

Question 12

what is stage 1 of sleep?

Answer 12

transition period between wakefulness and sleep
- begins when sleepers drift off
- waves of smaller amplitude and irregular frequency begin
- vertex spikes (sharp waves) appear
- heart rate slows, muscles relax, eyes roll slowly -> last several minutes

Question 13

what is stage 2 of sleep?

Answer 13

• breathing becomes more regular
• less sensitive to external stimulation
• EEG have burst of brain activity called sleep spindles (burst of 12-14 Hz waves) and K-complexes (sharp negative EEG potentials)

Question 14

what is stage 3 of sleep?

Answer 14

slow wave sleep where sleeps are hard to awaken
- EEG reveal large regular delta waves (large amplitude with slow waves about 1 per second)

Question 15

what is REM sleep?

Answer 15

eye dart rapidly under closed eyelids -> dreaming
- paralysis of motor systems (muscles relaxed)
- EEG show beta wave

Question 16

how many times do we cycle through the stages of sleep?

Answer 16

most people cycle through about 5 times
- total sleep time ranges from 7-8 hours with half is stage 2 sleep and 20% is REM sleep
- cycles last 90-110 minutes with cycles early in night have more stage 3 and later cycles have more REM

Question 17

what are dreams?

Answer 17

products of consciousness during sleep
- during dream, confusion of images and fantasies with reality
- spend 6 years of lives dreaming

Question 18

what are different REM dream?

Answer 18

vivid drams occur during REM sleep
- visual imagery: sounds, smell, and emotions -> feel like it’s there
nightmares: long, frightening dreams that awaken from REM

Question 19

what are the different brain areas associated with dreams?

Answer 19

1. more visual cortex activity (vivid visual imagery)
2. more amygdala activity (emotional content)
3. more M1 activity (“feeling” that we are acting)
4. more brain stem activity (preventing acting out dreams)
5. less PFC activity (illogical content)

Question 20

why do we have dreams?

Answer 20

activation-synthesis theory: dreams are result of brain’s attempts to make sense of random brain activity by synthesizing activity with stored memories

Question 21

what are non-REM dreams?

Answer 21

report thinking about problems rather than seeing themselves in mental movie
- night terrors: sudden arousals from stage 3 marked by fear and autonomic activity
- remember sense of crushing feeling on chest but don’t recall vivid dream
- common in children

Question 22

what can sleep deprivation lead to short term?

Answer 22

can impair function
- lead to microsleep (where people fall asleep for seconds or minutes)

Question 23

what are long term effects of sleep deprivation?

Answer 23

effects on cognitive performance and hippocampus activity
- hippocampus activity decreased with sleep deprivation
- hippocampus is key for memory so impair memory and cognitive performance

Question 24

how does less sleep lead to cognitive impairment?

Answer 24

poor sleep associated with Alzheimer’s disease
- as we age, amount of stage 3 sleep declines dramatically (at 60, it’s half as much as 20 & disappears by 90)
- lack of stage 3 leads to memory impairment and loss of growth hormone so cognitive decline

Question 25

how does the glymphatic system factor into sleep?

Answer 25

glymphatic clearance occurs primarily while we sleep (most active in stage 3) - may protect against Alzheimer's disease, stroke, and multiple sclerosis

Question 26

what parts of the brain generate sleep?

Answer 26

1. forebrain system: generates SWS 2. brainstem system: generates wakefulness in forebrain 3. pontine system: triggers REM sleep - hypothalamic system coordinates other three

Question 27

how does the forebrain generate SWS?

Answer 27

generated by basal forebrain - neurons in region become active at sleep onset and release GABA - GABA receptors also stimulated by general anesthetics which produce slow waves like SWS

Question 28

what wakes the forebrain?

Answer 28

reticular formation wakes forebrain - electrical stimulation of area will wake sleeping animal and lesions of area produce persistent sleep - forebrain and reticular formation regulate SWS and wakefulness

Question 29

what triggers REM sleep?

Answer 29

subcoeruleus (area of pons) responsible for REM sleep - some neurons in area only active during REM sleep - inhibit motor neurons & disable motor system during REM sleep

Question 30

how does the hypothalamus control other systems?

Answer 30

release hypocretin that controls other sleep systems -> loss leads to disorganized sleep

Question 31

what is narcolepsy?

Answer 31

symptoms: frequent, intense daytime sleep attacks, demonstrate cataplexy (sudden loss of muscle tone -> collapse), do not go through SWS before REM, and experience hallucinations and sleep paralysis treatment: altertness drugs and psychostimulants

Question 32

what causes narcolepsy?

Answer 32

humans with it lost 90% of hypocretin neurons - normally prevent transition from wakefulness directly into REM sleep) - key for governing sleep and wake cycles

Question 33

what is the hypothalamic sleep center?

Answer 33

hypocretin neurons project to basal forebrain, reticular formation, and subcoeruleus - axons also go to tuberomammillary nucleus (inhibition induces SWS) - contains hypocretin switch to determine wakefulness, non-REM sleep or REM sleep

Question 34

what is sleep paralysis?

Answer 34

brief inability to move just before falling asleep or just after waking up - may experience hallucinations (something is crushing chest) - never last more than a minute - pontine center may be continuing to impose muscle paralysis after wakefulness

Question 35

what are non-REM sleep disorders?

Answer 35

sleep disorders in children: night terrors and sleep enuresis (bed-wetting) - somnambulism (sleep walking): occurs during stage 3

Question 36

what is REM behavior disorder?

Answer 36

organized behavior in person who appears asleep (acting our their dream) - pontine center may not be able to impose muscle paralysis - may be followed by early symptoms of Parkinsons's disease or dementia - widespread damage of disease begins in brainstem region that imposes muscle atonia

Question 37

what is insomnia?

Answer 37

having trouble falling asleep or staying sleep - sleep-onset insomnia: difficulty falling asleep caused by situational factors - sleep-maintenance insomnia: difficulty staying asleep punctuated by frequency nighttime arousals caused by drugs or neurological and psychiatric factors

Question 38

what is sleep apnea?

Answer 38

breathing may cease for minute or so (blood O2 levels drop) - caused by: muscles in chest & diaphragm relax too much and changes in pacemaker respiratory neurons in brainstem) -> accompanied by snoring - increase risk of cognitive decline or Alzheimer's disease by more than 2 fold; also hypertension, cvd, and depression

Question 39

what is SIDS?

Answer 39

sudden unexpected death of healthy infant who stops breathing during sleep - raises from sleep apnea due to immature respiratory pacemaker system or arousal mechanisms - associated with abnormalities in brainstem serotonin systems - putting babies to sleep on back reduces incidents

Question 40

how do sleeping pills work?

Answer 40

bind to GABA receptors throughout brain side effects: produce marked changes in sleep patterns that persist for days after use; become ineffective; lead to daytime drowsiness and memory gaps

Question 41

what are sleep hygiene examples?

Answer 41

better sleep is achieved through good sleep habits Ex: develop regular routine to exploit circadian clock; avoid daytime naps & having caffeine at night; bedtime routine in quiet, dark environment; avoid use of phones and laptops at bedtime