A brief intro into the science of sleep

1. Sleep
Csilla Egri, KIN 306 Spring 2012
KIN306, 8:30am: excellent time to catch some Zzz’s

2. Outline
 What is sleep?
 What happens during sleep?
 What causes sleep?
 Functions of sleep??
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3. What is sleep?
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Sleep is an actively induced and highly
organized brain state with different phases.
Characterized by:
1.Reduced motor activity
2.Decreased response to stimulation
3.Stereotypic posture
4.Relatively easy reversibility

4. What happens during sleep?
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Pace-Schott Nature Reviews Neuroscience 2002
 We cycle thru
different stages of
sleep
 Non-REM
 Four stages
 “deep sleep”
 REM
 Rapid eye
movement
 Irregular heart rate
and breathing
 “paradoxical sleep”
 dream state?

5. What causes sleep?
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 Neuronal connections thru reticular
formation play a role
 Above pons – contributes to
wakefulness
 Below pons – has inhibitory
connections to wakefulness centers in
pons area reticular formation
 Role of sleep factors?
 accumulate in blood and CSF of sleep
deprived animals
 Induces sleep when injected into other
animals
 Circadian regulation of sleep wake cycles
 Does not cause sleep, but regulates
sleep timing
pons
thalamus

6. Effects on sleep: Caffeine
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 Caffeine has similar molecular
structure to adenosine
 Adenosine thought to be one
type of sleep factor
 Caffeine blocks adenosine
receptors (adenosine
antagonist)
 Stimulates wakefulness
 Potency and duration of effect
is highly variable and
subjective

7. Effects on sleep:
tetrahydrocannabinol7
 Chronic use of drug:
 Sleepiness, calming effect
 Reduced REM sleep
 Reduced dreaming/remembering of dreams
 Abrupt cessation of drug use
 Vivid dreams
 Sleep disturbances; insomnia, poor sleep quality
 Mechanism?
 Binds to CNS cannabinoid receptor CB1
 How/why this affects sleep is unknown

8. Why do we sleep?
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 Almost all animals require sleep
 Sleep deprivation causes irritability, reduced
cognitive functions, general malaise, death
 Sleep is required but physiological function is
speculative at best
 Neural maturation?
 Facilitation of learning, consolidation of
memories?
 Facilitation of development?
 Importance of REM sleep?
 Conservation of metabolic energy?

9. Objectives
After this lecture you should be able to:
 List the four characteristics of sleep
 Understand that sleep consists of different stages
 Compare the effects of caffeine and
tetrahydrocannabinol on sleep
 Describe some theories as to why we sleep
 Be really curious about the mechanism of sleep and
dreams and pursue a career as a researcher
After this section of the course you should:
 Be really fascinated about the complexities, intricacies
and mysteries of nervous system physiology and
pathophysiology and pursue a career as a scientist
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10. 10
1. If the brainstem is cut as per the dotted line in slide 5,
would sleep be stimulated or inhibited?
2. Caffeine binds to ______________ receptors and
stimulates wakefulness.
3. Why is REM sleep sometimes referred to as
paradoxical sleep?
Test your knowledge