Upload
csilla-egri
View
166
Download
1
Embed Size (px)
Citation preview
Sleep
Csilla Egri, KIN 306 Spring 2012
KIN306, 8:30am: excellent time to catch some Zzz’s
Outline
What is sleep? What happens during sleep? What causes sleep? Functions of sleep??
2
What is sleep?3
Sleep is an actively induced and highly organized brain state with different phases.
Characterized by:1.Reduced motor activity2.Decreased response to stimulation3.Stereotypic posture4.Relatively easy reversibility
What happens during sleep?
4
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?
What causes sleep?5
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
Effects on sleep: Caffeine6
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
Effects on sleep: tetrahydrocannabinol
7
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
Why do we sleep?8
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?
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
9
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