Introduction to sleep

Question 1

Whats the OED definiton of sleep?

Answer 1

a condition of body and mind which typically recurs for several hours every night in which the nervous system is inactive, the eyes closed, the postrual muscles relaxed, and conciousness practically suspends

Question 2

Describe the loss of perception of senses during sleep

Answer 2

-senses continue
-thalamus blocks sensory signals travelling to the cortex where they are normally conciously perceived

Question 3

What is unihemispheric sleep?

Answer 3

some species have evolved the ability to uncouple the two hemispheres of the brain

Question 4

What are the four theories of sleep?

Answer 4

-evolutionary
-energy conservation
-restoration
-brain plasticity

Question 5

Describe the evolutionary theory of sleep

Answer 5

-inactivity at night is an adaption that has a survival function, as animals which stay quiet during vunerable periods and have an advantage over animals remaining active

-reduced accidents when active in the dark
-reduced predation
-conversly there is a reduced ability to react to threat whilst asleep

Question 6

Describe the energy conservation theory

Answer 6

-the primary function of sleep is to reduce an animals energy demand and expenditure
-provides periods of inactivity
-some animals-hibernation acts as a mean of conserving energy

Question 7

Describe the restorative theory

Answer 7

-sleep provides and opportunity for the body to repair and rejuvinate
-many major restorative functions such as tissue repair and growth hormone release occur during sleep

Question 8

describe the restorative theory in more detail

Answer 8

-rate of cells divion and protein synthesis increases during sleep
-NREM sleep is important for restoring physiological functions
-Rem sleep is essential in restoring brain systems
-following sleep deprivation there is an increase in periods of REM sleep

Question 9

Describe the glymphatic system

Answer 9

-drains toxins from the brain in a similar manner as the lymphatic system
-more active during sleep
-glial cells that are distributed throughgout the brain shrink during NREM sleep to increase space between the neurons, so allowing cerebral spinal fluid to flush out toxins

Question 10

describe the brain plasticity theory

Answer 10

-sleep is correlated to changes in structure and organisation of brain plasticity

-sleep is critical in the brain development of infants and young children

-sleep deprivation reduced ability to learn and perform tasks

Question 11

Whats the relationship between sleep and memory?

Answer 11

-sleep favours processes of memory consolidation that cant occur whilst awake due to environmental demands
-sleep deprivation impairs cognitive function
-REM and SWS sleep are the most important in memory consolidation

Question 12

Describe the EEG

Answer 12

-1982
-elecrtoencephalogram by Hans berger
-electrodes plassed on the scalp to record electrical activity of the brain, differences between sleep and awake states recorded

-used to instigate different types of sleep by determining different waveforms

Question 13

Name the different brain wave types and occurance

Answer 13

infraslow-unknown
delta-sleep
theta-sleep
alpha-awake and resting
beta-awake-cognitive tasks
gamma-awake-peak concentration

Question 14

List the wave speed in HZ of the different brain wave types

Answer 14

infraslow-<0.5
delta- 0.5-3.0
theta-3.0-8.0
alpha-8.0-12.0
beta-12.0-38.0
gamma-38.0-42.0

Question 15

What are the two stages of sleep?

Answer 15

-REM
-NREM (non rem)

Question 16

What are the stages of NREM?

Answer 16

stage 1- transition from wakefullness to sleep
stage 2-first unequivocal stage of sleep
stage 3-slow wave sleep

Question 17

Describe NREM sleep stage 1

Answer 17

-first 1-10 mins of sleep
-2-5% of sleep

Question 18

What are some features of NREM sleep stage 1?

Answer 18

-body muscles are functional
-breathing and HR slow down and become regular
-BP and brain temp decrease
-hyponogogic jerk

Question 19

Describe the EEG changes in NREM stage 1

Answer 19

brain activity slows, transisiton from beta to gamma waves, slower and more synchronized alpha waved when eyes closed and then onto theta waves

Question 20

Describe NREM sleep stage 2

Answer 20

-last 10-25 mins in the intial cycle of sleep and lengethens with each successive cycle
-45-55% of sleep

Question 21

List some special features of NREM sleep stage 2

Answer 21

-HR slows
-Body temp drops
-metabolic functions slow to prepare for deep sleep
-harder to wake

Question 22

Describe the EEG changes during NREM sleep stage 2

Answer 22

-Theta waves form
-sleep spindles-short burst of brain activity of 12-14HZ lasting 0.5s
-K complex occurs every 1-2 mins
-protect sleep, supress outside stimuli and help memotry consolidation and info processing

Question 23

Describe NREM sleep stage 3

Answer 23

-begins at 35-45 mins of sleep
-spend aprrox 15-20% sleep time here

Question 24

List some special features of NREM sleep stage 3

Answer 24

-delta sleep
temp,Breathing rate, HR, Bp at lowest levels
-dreaming
-hard to rouse sleeper
-stage where parasomnias occur(sleep talking and walking)
-info proccessing and memory consolidation occur
-children and young adults have more stage 3 sleep than adults

Question 25

Describe the EEG changes of NREM sleep stage 3

Answer 25

-delta brain waves
-occasional sleep spindles

Question 26

Describe REM sleep

Answer 26

-begins after about 90 mins of sleep and lasts about 10 mins
-most REM occurs during the final third of sleep
-20% of sleep is spent in REM (babies 80%)

Question 27

Describe the special features of REM sleep

Answer 27

-random rapid eye movement
-abscence of muscle tone-paralysed skeletal muscles-antonia
-highly vivid and emotional dreams
-heart,BP and respiratory rates increase and bcome irregular
-core temp is poorly regulated and drops

Question 28

Describe the EEG changes during REM sleep

Answer 28

-low amplitude, mixed frequency
-brain waves-theta,alpha and beta
-REM sleep is known as paradoxical sleep as brain waves look similar to the awake state
-occasional sleep spindles

Question 29

What is sleep paralysis?

Answer 29

-sleep disorder where patient is awake during REM sleep so is unable to speak or more
-often accompanied by hallucinations, typical sensations of being suffocated or of dread

Question 30

What societal changes cause sleep deprivation?

Answer 30

-work ethic/shift pattern
-early school start time
-24/7 entertainment

Question 31

What technological changes cause sleep deprivation?

Answer 31

-artificial light
-blue light

Question 32

List some consequences of sleep deprivation

Answer 32

-reduced cognitive function
-reduced memory consolidation
-reduced motor control
-reduced immune system
-increased anxiety
-depression
-decreased sex drive
-poor dietary intake

Question 33

Good bedtime routines

Answer 33

-go to bed at the same time each day
-set the alarm for the same time every day
-dont hit snooze
-dont nap during the day
-dont go to bed unless your sleepy

Question 34

List some good bedroom environment factors

Answer 34

-quiet and relaxing bedroom
-keep the room at a cool and comfortable tenperature
-make sure the matress is comfortable
use your bed only for sleep and sex
-make sure the room is dark

Question 35

Describe the caffeine inhibition of homeostatic drive

Answer 35

caffeine blocks adenosine receptor binding sites in the brain thus temporally reducing sleep pressure

-but adenosine accumulation continues if sleep does not occur

Question 36

Why is blue light bad before bed?

Answer 36

-suppresses melatonin production

Question 37

give a summary of factors that contribute towards sleep hygiene

Answer 37

-effects of light on melatonin levels
-temperature
-sedatives or stimulants
-eating
-excersise
-drinking/urination
-pain
-clock watching

Question 38

How can we investigate how well someone sleeps?

Answer 38

-patient history
-sleep diary
-sleep study
-actigraphy
-overnight oximetry
-multichannel sleep recording
-full polysomnogrpahy