At what age do humans sleep more?
During infancy
Infant sleep cycle characterized as
- Shorter sleep cycles
- More REM sleep—50%,
- A 24-hour rhythm is generally evident by 16 weeks of age
- Unlike most adults, human infants can move directly from an awake state to REM sleep
- Lack of atonia during REM
- Unstable patterns of sleep prior to 16 weeks
- Stable and prolonged patterns of sleep to 16 weeks
What happens when people age?
Total time asleep declines, and the number of awakenings increases
What happens in stage 3 sleep within old people?
- At age 60, only half as much time as at age 20
- By age 90, it has disappeared
What happens when you are sleep deprived whether it’s partially or totally?
- Increased irritability (mood)
- Difficulty in concentrating (working memory)
- Episodes of disorientation
- Effects vary with age and other factors.
What is sleep recovery?
The process of sleeping more than normally after a period of sleep deprivation, as though in compensation
What happens to your REM sleep during the recovery phase?
You have more intense sleep with a greater number of rapid eye movements per period of time.
Sustained Sleep Deprevation
In Humans: Increase in hypertension, metabolic disruption, weight gain, Type 2 diabetes, and immunosupression
What is Fatal Familial insomnia?
When people stop sleeping and dies 7-24 months after the onset of insomnia; inherited in midlife
What are the functions ascribed with sleep?
- Energy Conservation
- Niche adaptation
- Body and brain restoration
- Memory consolidation
Energy Conservation
We use up less energy when we sleep than when we’re awake
Niche adaptation
Sleep forces species to conform to the ecological niche to which they are adapted (avoid predation)
Body and brain restoration
- The rebuilding or restoration of materials used during waking, such as proteins
- Most growth hormone is only released during SWS.
- Glial cells more readily filter toxins from the CSF
- Cerebrospinal Fluid
Memory consolidation
- Sleep during the interval between learning and recall improves retention
- Learning of perceptual skills (recognition, puzzles, mazes) is improved by a period of REM sleep
- Consolidation of declarative memory tasks and complicated motor skills benefits from SWS
- REM sleep is not necessary for learning
What four interacting neural systems underline sleep
Forebrain system
Brainsystem
Pontine system
Hypothalamic system
Forebrain system
Generates SWS
* Neurons in this region become active at sleep onset and release GABA. * GABA activates receptors in the nearby tuberomamillary nucleus * These GABA A receptors are also stimulated by general anesthetics, which produce slow waves resembling SWS
A brainstem system
Activates the sleeping forebrain into wakefulness
* The reticular formation wakes up the forebrain
* Electrical stimulation of this area will wake up sleeping animals.
* Lesions of this area produce persistent sleep.
* Together, the forebrain and reticular formation seem to regulate SWS and wakefulness.
A pontine system
System that triggers REM sleep
* An area of the pons, Subcoerulus, is responsible for REM sleep.
* Some neurons in this region are only active during REM sleep.
* They inhibit motor neurons to keep them from firing, disabling the motor system during REM sleep
A hypothalamic system
System that coordinates the other three brain regions to determine which state we’re in
What did the Transection(cerveau isole) experiments show?
That different sleep systems originate in different parts of the brain (Bremer, 1938)
What is the isolated brain made from?
An incision between the medulla and the spinal cord; Animals showed signs of sleep and wakefulness, proving that the networks reside in the brain
How does the for rain generate slow wave sleep?
Since the electrical activity in the forebrain showed constant SWS, but no signs of wakefulness or REM, it shows that the forebrain can generate SWS
