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LCRS Neuroscience > Sleep > Flashcards

Sleep Flashcards

1
Q

What are the typical behavioural criteria of sleep?

A

Stereotypic or species-specific posture
Minimal movement
Reduced responsiveness to external stimuli
Reversible with stimulation- unlike coma, anaesthesia or death
Brain is very active when you are asleep

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2
Q

What 3 things are used to monitor sleep?

A

Electorencephalogramm
Electrooculogramm
Electromyogramm

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3
Q

What are the 3 measurements like when you are awake?

A

Quite fast brain rhythm in EEG (beta rhythm)- upto 30Hz

Reasonable amount of muscle tone because you are maintaining posture and ready for action

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4
Q

What are stage 1 and 2 of sleep?

A

Light sleep

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5
Q

What are the 3 measurements like in stage 1 and 2 (NREM)?

A

Person is becoming more and more drowsy and EEG activity is slowing. Gradually go from beta activity to theta activity (4-8 Hz), no eye movements and general muscle activity has been reduced considerably

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6
Q

What are the 3 measurements like in stage 3 and 4 sleep?

A

Translation from theta activity to delta activity. Slowest rhythm (1 Hz), there is minimal eye movement at this point. There is continued relaxation of the muscles- this is very deep sleep

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7
Q

What are the 3 measurements like in stage 5 sleep (REM)?

A

Brain activity shifts abruptly back to fast rhythm, quite similar to the activity you see in awake subjects. You get rapid eye movement even though the subject is asleep. Muscle activity is at its lowest so person is basically paralysed

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8
Q

What are the first four stages of sleep called?

A

Non-REM

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9
Q

How long is a single sleep cycle?

A

1-1.5 hours

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10
Q

How does distribution of slow wave sleep and REM sleep change throughout the night?

A

You get more slow wave sleep at beginning of night and more REM sleep at end of the night

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11
Q

How does heart rate and respiration rate change in different stages of sleep?

A

Heart rate is slow during slow wave sleep and faster during REM sleep and same with respiration rate

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12
Q

What is consciousness mainly controlled by?

A

Reticular activating system

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13
Q

Where does the reticular activating system start?

A

In the brainstem then projects up and influences activity of cerebral cortex

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14
Q

How does the reticular activating system influence activity in cerebral cortex?

A

It can do it directly or through indirect input via intralaminar nuclei in the thalamus

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15
Q

What two nuclei in the hypothalamus influence the RAS and so control the sleep-wake cycle?

A

Lateral hypothalamus- excitatory input to RAS. Active during day and enables higher level of activity in cortex when awake
Venterolateral preoptic nucleus- negative effect on RAS, promotes sleep.
Antagonistic relationship between these two nuclei- when one is active it inhibits other

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16
Q

What does the suprachiasmatic nucleus do?

A

Synchronises sleep with falling light level

17
Q

How does the suprachiasmatic nucleus work?

A

It receives input from the retina- not usual rods/cones but special type of ganglion cell- as light levels fall, suprachiasmatic nucleus becomes more active and activates nuclei within hypothalamus. It will inhibit LH nucleus and will stimulate the VLP nucleus so towards end of day, you become more sleepy.
Also has direct effect on RAS resulting in reduction of traffic
Projection to the pineal gland which it activates towards end of day and this secretes higher levle of melatonin and continues to secrete through the night. Melatonin adjusts various physiological processes in the body that fit with sleep

18
Q

How necessary is sleep?

A

All animals sleep
Sleep deprivation is detrimental
Sleep is regulated accurately

19
Q

What are the effects of sleep deprivation?

A

Sleepiness, irritability
Performance decrements/increased risk of errors and accidents
Concentration/learning difficulties
Glucose intolerance- risk of diabetes
Reduced leptin/increased appetite- risk of obesity
Hallucinations (after long sleep deprivation)
Death- rats (14-40 day)
Humans- fatal familial insomnia

20
Q

What happens after loss of sleep?

A

Sleep is regulated:
Reduced latency to sleep onset (if you’ve lost a night’s sleep you will go to bed earlier the next day
Increase of slow wave sleep (NREM)- if you’ve been sleep deprived then are given opportunity to sleep, you will sleep for longer
Increase of REM sleep (after selective REM sleep deprivation)

21
Q

What are the functions of sleep?

A

Restoration and recovery- but active individuals do not sleep more
Energy conservation- 10% drop in BMR but just lying still and not sleeping does this as well
Predator avoidance- but just hiding in a corner awake will also do this

22
Q

When do you dream?

A

In both REM and NREM sleep but mostly during REM sleep

23
Q

When are dreams more easily recalled?

A

During REM sleep

24
Q

How do dreams differ from real life?

A

They tend to be more emotional- brain activity in the limbic system is higher than in the frontal lobe during dreams

25
Q

What are most cases of insomina like?

A

Most are transient

26
Q

What are the causes of chronic insomnia?

A

Physiological e.g. sleep apnoea, chronic pain

Brain dysfunction e.g. depression, fatal familial insomina and night working

27
Q

What treatments for insomnia are there?

A

Try and remove the cause if possible
If not, pharmaceutical treatment- hypnotics which mainly work by enhancing the inhibitory circuits in the brain- GABAergic circuits

28
Q

What is narcolepsy?

A

Falling asleep repeatedly during the day and disturbed sleep during the night

29
Q

What is cataplexy?

A

Sudden onset of muscle weakness that may be precipitated by excitement or emotion
Sometimes just one part of body, sometimes most of the muscles can suddenly relax and person can fall over

30
Q

What is thought to be happening in cataplexy?

A

Dysfunctional control of REM sleep and people go straight into REM sleep without other stages first

31
Q

What is thought to be the cause of narcolepsy or cataplexy?

A

Not well understood- seems to be orexin deficiency which is a neuropeptide that is used by the lateral hypothalamus. This could be genetic or autoimmune

LCRS Neuroscience (18 decks)

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