Sleep

Question 1

What are circadian rhythms?

Answer 1

• functions that display a rhythm of about 24 hours

Question 2

diurnal

Answer 2

active during the light

Question 3

nocturnal

Answer 3

active during the dark

Question 4

Rhythms may be…

Answer 4

• behavioral,
• physiological, or
• biochemical

Question 5

What generates body rhythms

Answer 5

An endogenous clock

Question 6

What do rhythms entrain to

Answer 6

light-dark cycles

Question 7

biological clock leads to…

Answer 7

• precise tmiing
• endogenous clock is not quite 24 hr
• is entrained (set) to light/dark cycles

Question 8

Biological clocks- rat study

Answer 8

• When researches shift the light cycle for rats, behavior also shifts
• with continuous dim light, behavior becomes free running

Question 9

What allows for entrainment?

Answer 9

• light (visual input)
• meals
• sleep
• jobs/class (overnight shifts)
• activity/exercise

several of these inputs are also regulated by the biological clock

Question 10

What is disrupted in animals with SCN lesions?

Answer 10

circadian rhythms

Question 11

Where is the biological clock located?

Answer 11

In the SCN- located above the optic chiasm in the hypothalamus

Question 12

What can isolated SCN neurons do?

Answer 12

• maintain electrical activity synchronized to the previous light cycle

Question 13

What do most retinal ganglion cells contain, and what does this do?

Answer 13

most retinal ganglion cells contain melanopsin, a special photopigment that makes them sensitive to light

Question 14

What does the retinohypothalmic pathway consist of?

Answer 14

retinal ganglion cells that project to the SCN

Question 15

ganglion cells in the retinohypothalamic pathway rely on rods and cones: T/F

Answer 15

false, they DO NOT rely on rods and cones

Question 16

Retinohypothalamic Pathway two steps

Answer 16

1. Light causes glutamate release in SCN
2. Synchronizes SCN neurons to each other and light/dark cycle

Question 17

How many distinct classes of sleep are there? What are they called?

Answer 17

• There are two distinct classes of sleep
• Non-REM sleep and REM sleep

Question 18

What is non-REM (NREM) sleep?

Answer 18

• characterized by lack of rapid eye movements
• can be divided into three stages

Question 19

What is Rapid-eye-movement sleep (REM)?

Answer 19

• characterized by….
• small-amplitude, fast-EEG waves
• no postural tension
• rapid eye movements

Question 20

Describe the pattern of activity in an awake person

Answer 20

• contains many frequencies
• dominated by a mix of high frequency (15-20Hz) and low amplitude waves
• this is known as beta activity or desynchronized EEG

Question 21

An alert, awake human’s EEG is…

Answer 21

desynchronized (aka beta activity)

Question 22

When does stage 1 sleep begin?

Answer 22

when vertex spikes appear (drowsiness)

Question 23

What are the symptoms associated w stage 1 sleep?

Answer 23

• heart rate slows
• muscle tension decreases
• eyes roll about

Question 24

How long does stage 1 sleep last?

Answer 24

several minutes

Question 25

When does alpha rhythm appear? How does it appear on an EEG?

Answer 25

* alpha rhythm appears during relaxation * regular oscillation at 8-12 Hz

Question 26

If a person is woken up during stage 1 or 2, how would they react?

Answer 26

the person may deny they were sleeping, even though they had failed to respond to signals

Question 27

What phenomena occur during stage 2 sleep?

Answer 27

K-complexes and sleep spindles

Question 28

What are sleep spindles? What stage of sleep are they associated with?

Answer 28

* waves of 12-14 Hz that occur in bursts * looks like densely packed scribbles * seen in stage 2

Question 29

What are K-complexes and what stage of sleep do they appear?

Answer 29

* sharp negative EEG potentials * appear in NREM 2

Question 30

When do delta waves dominate?

Answer 30

by late Stage 3 sleep

Question 31

What is another term for stage 3 sleep?

Answer 31

slow-wave sleep

Question 32

How often do delta waves occur?

Answer 32

about once per secone

Question 33

What is stage 3 sleep defined by?

Answer 33

* the appearance of large-amplitude, very slow waves called delta waves

Question 34

What is another term for REM sleep and why is it termed that?

Answer 34

* paradoxical sleep * due to the mismatch betwen brain activity that resembles an awake person and the lack of muscle activity

Question 35

What characterizes REM sleep?

Answer 35

* active EEG w small-amplitude, high-frequency waves, like an awake person * muscles are relaxed- flaccid and unresponsive

Question 36

How does sleep change throughout the night?

Answer 36

* progressive lengthening of REM sleep * loss of stage 3 sleep as the night goes on

Question 37

Young adult sleep

Answer 37

* Young adults tend to be late risers * young adults should sleep 8 hours per night

Question 38

How does sleep change with age?

Answer 38

* waking increases * REM sleep decreases more than non-REM * elderly often complain of insomnia

Question 39

Why do we sleep?

Answer 39

* energy conservation * niche adaptation * body restoration * memory consolidation

Question 40

# Why do we sleep? Energy conservation

Answer 40

reduced... * muscle tension * heart rate * blood pressure

Question 41

# Why do we sleep? Niche adaptation

Answer 41

nocturnal vs diurnal

Question 42

# Why do we sleep? body restoration

Answer 42

toxin build-up in CSF flows out of brain faster

Question 43

# Why do we sleep? Memory consolidation

Answer 43

* sleep helps you retain information * neuronal activity patterns of learning are repeated during Stage 3 * Synaptic remodeling

Question 44

Sleep regulation-basal forebrain

Answer 44

* GABA in the basal forebrain (including hypothalamus, cortex): * generates NREM sleep (in particular SWS) * inhibits the reticular formation * "Electrical stimulation of the basal forebrain makes animals sleepy, while lesions of this region induce insomnia"

Question 45

Sleep regulation- reticular formation

Answer 45

* reticular formation includes the medulla and thalamus * sends signals to the basal forebrain * promotes wakefulness

Question 46

Sleep regulation- PONS (subcoeruleus)

Answer 46

* triggers REM by sending signals to basal forebrain * Inhibits motor neurons (loss of postural tension)

Question 47

Sleep regulation- Hypothalamus

Answer 47

* hypocretin/orexin cells send information to the 3 other sleep centers * control switch between awake, NREM, REM (narcolepsy and sleep paralysis) * "Sends axons to the other three sleep centers and seems to coordinate them, enforcing the patterns of sleep. Loss of hypocretin can lead to disorganized sleep, such as REM- like muscle atonia while still awake (in narcolepsy)