Why Do We Sleep?
Time scales for sleep duration are set by..
THE BRAIN (NOT the whole metabolic rate).
What is a third theory explaining why we sleep?
Thermoregulation:
Sleep cools the brain and the body
Slow-wave sleep induces the brain and body cooling
What happens to rats deprived of sleep?
They lose their weight and become scrawny
They are unable to maintain their body temperature
Rats deprived of all sleep died in 18-32 days
Rats selectively deprived of REM sleep died in 16-54 days (37-day average)
What is (Theoretically) the primary function of sleep?
Brain maintenance
Repair
Reorganization
What is sleep characterized by?
1) Reduced activity
2) Immobile posture
3) Eye closure
4) Readily reversible reduction in sensitivity to external stimuli
5) Readily reversible loss of consciousness awareness
What goes on in the brain during sleep?
Energy is restored
Brain maintenance
Memory consolidation
Brain clearance- brain removes toxic chemicals and waste
What is Unihemispheric sleep?
One-sided sleep
The body is paralyzed on one side of the brain at a time
2 sides of the brain uncouple and operate independently
Stay alert with half of the brain while the other half is in deep sleep
This mainly occurs in mammals, dolphins, and birds
What is the molecule in which energy is stored?
ATP
Why do we sleep?
No one knows for sure why, but it is necessary.
It is a necessity, mystery, and luxury.
Sleep has a restorative function for biological functions produced only during sleep.
What is memory consolidation?
Fact-based memory and physiology-based tasks are taken from short-term memory to long-term memory
What is Polyphasic sleep?
Alternative intervals of sleep and activity
What happens when the adenosine levels in the brain increase?
We become more tired and sleepy
What is a theory explaining why we sleep?
Energy Conservation:
Sleep has evolved to reduce energy commands
NREM has a lower metabolic cost than being awake
As metabolic rate increases as animals get smaller, the prediction would be that sleep should also increase in smaller animals
Sleep helps to conserve energy by lowering metabolic rates
Why does the body need sleep?
The brain and body become fatigued and sluggish
Cognitive impairment
Risk of Alzheimer’s disease
Forgetfulness
Integration of daily learning
Impairment of creativity and problem-solving as well
What is Monophasic sleep?
One long interval during a 24 hour period
What is caffeine considered?
An adenosine blocker
Temporarily blocks the bonds from breaking down
What is a second theory explaining why we sleep?
Energy Restoration:
The brain uses more energy than any other organ
The brain is only 2-3% of the weight of the human body
The brain uses 20-25% of the oxygen and energy consumed
The molecule in which energy is stored is ATP
During sleep, we recover and restore our high energy bonds
Is sleep necessary for life?
I think it is safe to say that sleep is ABSOLUTELY necessary for life and all its functions!
What kind of sleep do humans have when there is no electricity?
Biphasic sleep
Based on a Dawn-Dusk schedule
What does an electroencephalogram do?
Measures brain waves during sleep
Records electrical activity of the brain
(EEG)