Circadian Rhythms

Question 1

What is a circadian rhythm? defne.g.

Answer 1

“internal clock” (aka) endogenous that control biological rhythms have periods of about a day (24 hrs)e.g. blood pressure, metabolism, hormone patterns.they are influenced by light, but are also internal (put a sunflower in closet, still opens closes right time)

Question 2

characteristics of circadian rhythmslight?.age?.all? but?.genetics?.not affected by?

Answer 2

.they are influenced by light, but are also internal (put a sunflower in closet, still opens closes right time).persist from youth to senescence (old age).all living organisms, but different for each species (prey or predator, for e.g.?).genetically determined.not affected by alcohol

Question 3

Describe Aschoff & Wever Studybasic?.no?.sleep schedule?.indicate sleep how?.monitored?

Answer 3

.1960s, lived in underground bunker w/o natural light for month.no clocks, other people, social cues, ZEITGEBERS.sleep whenever, but no nap.indicate sleep by radio contact.EEG and body temperature

Question 4

What did Aschoff & Wever found about circadian sleep rhythm?length?moved? e.g.?reset?

Answer 4

24 hours in length about, plus a bit.moved forward in time without light (28 days for them was actually 29 days in bunker).we must RESET our circadian rhythm to 24 hours!

Question 5

Zeitgebersexamples?

Answer 5

time cues from environment, literally time givers.light, sun.alarm clock.jobs/school.daytime/environmental noise

Question 6

jet lag?

Answer 6

disturbance of circadian rhythms caused by rapid long-distance travel by plane

Question 7

jet lag: phase delaydirection?difficulty?why?

Answer 7

travelling west.easier, b/c easier to stay up later than go to sleep earlier.e.g. paris (2am) to boston (9pm)

Question 8

jet lag: phase advancedirection?difficulty?why?

Answer 8

.travelling east.harder, b/c sleep earlier harder than sleeping later.e.g. boston (9pm) to paris (2am)

Question 9

tips for jet lag

Answer 9

.takes day for each hour circadian rhythm out of sync.easier for owls than larks.melatonin can make shift happen quicker.if stay up whole night/day, and fall asleep next day, resets faster.eat protein to stay awake, carbohydrates to fall asleep.if take nap few hours b4 leaving, handle lack of sleep better

Question 10

Describe Seissler’s classic study on shift work.measured?.sample?.original schedule?.changed to?

Answer 10

.measured worker satisfaction/health/productivity.using 85 rotating-shift males (19-68) in industrial plant.original schedule, phase advance shifts changed weekly.changed to phase delay (one group on 3 wk rotation, 1 grp on 1 wk rotation)

Question 11

results of Seissler’s classic study on shift work

Answer 11

.after 3 months, asked how workers fared with the changes.ALL reported more satisfaction.3 wk rotation reported GREATER satisfaction, health, & productivity! (opposed to 1wk)

Question 12

why was seissler study important?

Answer 12

showed phase delay schedules better for shift workers.also good because shift workers implicated in manys serious errors.

Question 13

How is the circadian rhythm entrained?how use pineal gland?how do we know? (2)

Answer 13

SCN receives input from optic nerve of rhythms of light and dark, which then synchronizes circadian clock to 24hr pattern.works with pineal gland to secrete melatonin, controls it.know b/c cut above Pons in brain, circadian control of sleep is disrupted.damage SCN, circadian rhythms ABOLISHED

Question 14

what is the SCN?.maintains

Answer 14

Suprachiasmatic Nucleus.small structure/cluster of cells in the hypothalamus.maintains rhythm of sleep and wakefulness even in absence of light (blind ppl)

Question 15

How does the pineal gland work?melatonin for sleepiness?used for?

Answer 15

.secretes lots of melatonin at night, in the ABSENCE of light.secretes little or none during the day.melatonin NOT essential for sleepiness, but reliably brings it on.used for travel and by the blind (altho in some cases they can still entrain w/ light and dark b/c have ganglion cells!)

Question 16

Before, it was believed that rods and cones triggered SCN activity. What actually does it? How?What kind of light stimulates them?

Answer 16

.ganglion cells! & melanopsin.reacts to light and transmits neural signals to SCN helping to reset circadian clock.stimulated by light from blue end of spectrum (iphones!!!)

Question 17

Temperature rhythms of sleep (3): 1. sleep itself cools the bodydiminishes?no? when cold?initiated when warm?

Answer 17

1. sleep itself cools the body.heat production AND conservation diminishes.no muscular activity, so no shiver when cold!.but sweating initiated when warm

Question 18

Temperature rhythms of sleep (3): 2. NO regulation of body temp during REM sleep.if body cools during REM?.neurons in hypothalamus?.partly why small animals?.but babies?

Answer 18

.if body cools during REM, warmed during NREM.neurons in hypothalamus lose sensitivity to heat/cold during REM, are “resting”.partly why small animals have smaller REM cycles, b/c easy to lose heat! (also animals in colder climates).but babies have lots of REM, so need to keep them super warm wrapped in blankets!

Question 19

Temperature rhythms of sleep (3): 3. NREM body temp?

Answer 19

3. In NREM, body temperature is lower (funtion of circadian rhythm and sleeping), but there is still regulation

Question 20

what does ontogeny of sleep mean?

Answer 20

the development of sleep over the lifespan

Question 21

Newborns.first recognizable sleep in humans? .newborns go straight? (half?).features of REM?.length of sleep? total and at a time? gradually?

Answer 21

.REM first recognizable sleep, before birth almost all REM sleep.newborns go straight into REM at sleep onset, no cycling (half of sleep is REM).features of REM exaggerated b/c inhibitions aren’t as good, jerk around, eyes flitter, half open.16hrs total sleep for newborns, may only 2hrs at a time b/c waking aids their development.gradually sleep episodes get longer, by 6 mo, can sleep 8hrs or so a night

Question 22

When does NREM sleep arrive in infants?

Answer 22

3mo. old.no sleep spindles or K complexes yet though

Question 23

Early Childhood (1-5yrs).diurnal cycle (daily cycle)?.cycle thru? REM?.hard to wake in? normal at this age?

Answer 23

.diurnal cycle = 10-12hrs a night w/ a daytime nap.cycle real quick thru stages 1-3 into stage 4 (where growth hormone released). much less REM now.hard to wake in stage 4 sleep, normal to have sleep walk, night terrors, talk in sleep, bed wet

Question 24

Middle childhood (5-12yrs).how many hours a night?.typical this age?

Answer 24

.9-10.5 hrs of sleep a night adequate.teeth grinding and sleep walking this age!

Question 25

Adolescence (12-18).independence?.sleeping in?

Answer 25

Tend to assert independence through sleep times (myself included!), and sleeping in late happens much more this time, sleeping in way late on weekends

Question 26

Early Adulthood (18-30).consistency?.become aware?

Answer 26

.fair amount of consistency within sleepers.adults start to become aware of their own individual sleep times (lark, owl, sleep times and lengths)

Question 27

Early Middle Age (30-45).sleep length?.difficulty to sleep?.alertness? refreshed?.lifestyle changes attribution?

Answer 27

.sleep is shorter and shallower, w/ a drop in stage 4 sleep.harder to fall asleep whenever, even naps, and waken more easily.takes longer to become alert after waking, and not as refreshed after waking.can be attributed to lifestyle changes like children, medication, tolerate drugs/liquor, weight gain (apnea maybe), more sedentary

Question 28

Late middle age (45-60).sleep deprivation?.bed time?.length?.wake up?.differences in stages?

Answer 28

.sleep deprivation more disturbing at 45-60.go to bed earlier, for less time (7hrs avg now).awaken more, bladders smaller.little stage 4 and more stage 1 (in limbo)

Question 29

Old age (60yrs).sleep continues to?.fewer? so?.illness?

Answer 29

.sleep continues to decline.fewer involvements so less physical exercise.chronic illnesses and medication