Sleep Flashcards
What is sleep?
Normal, recurring, reversible state in which there is an inability to respond to the external environment.
What is unconsciousness?
Lack of full awareness of self and environment.
What is consciousness?
Awareness of self and environment, and the ability to respond when stimulated.
What is REM sleep?
Rapid eye movement.
When does most NREM sleep occur?
At the start of the night.
What percentage of sleep for young adults is NREM?
Around 3/4.
Describe non rapid eye movement sleep.
- Synchronised rhythmic electroencephalography (EEG) activity, partial muscle relaxation and reduced cerebral blood flow.
- Reduced heart rate, blood pressure and tidal volumes.
- Some non-narrative images.
Describe REM sleep.
- Occurs mostly at the end of the night.
- EEG shows fast activity, fMRI (functional MRI) shows increased brain activity - similar to wakefulness.
- Atonic muscles with the exception of diaphragm and extraocular muscles.
- Increased cerebral blood flow and impaired thermal regulation.
- Narrative dreaming.
Why is deep sleep essential?
To allow cortex recovery after busy day.
What is the function of REM sleep?
- Mainly for early brain development.
- Likely dispensible.
- Seen as “non-wakefulness, not sleep”.
Which common drugs suppress REM sleep with no effect?
Tricyclics.
Neonates spend 16 hours a day asleep, what percentage of this is REM sleep?
50%.
Describe sleeping pattern of the elderly.
Increased awakenings, reduced REM latency and total sleep time and daytime napping.
What controls sleep?
- Biology and physiology.
NOT psychology. - Circadian rhythm is important for sleep-wake, appetite and hormone secretion.
Function of REM sleep?
- Consolidates memory and possibly deletes unnecessary memory files.
- Maintains immunocompetence.
What are circadian rhythms?
Endogenously controlled human processes.
e.g. sleep-wake, appetite, body temperature and hormone secretion, alertness.
Normal circadian rhythm lasts how long?
24 hours and 20 mins.
What entrains the body clock?
- Light. Uses retinal ganglion cells projecting to suprachiasmatic nucleus.
- Non-rod, non-cone cells.
There is no clinical evidence to suggest that muscle recovery occurs during sleep, but what does sleep help to repair?
Tissue repair.
What peaks during sleep?
- Cell division.
- Skin mitosis.
Most effects of lack sleep affect which part of the cortex?
Prefrontal - impaired alertness.
However, old and well rehearsed tasks, routine behaviour and logic tasks remain unaffected.
Effects of lack of sleep?
- Irritable, suspicious.
- Visual illusions.
- Microsleeps and concentration lapses.
What percentage of RTAs attended by police are sleep related?
= 10%.
Most are acute deprivation.
Double on non-urban roads.
Most likely cause of accidental death at work?
Truck driver falling asleep at wheel.
Total loss of truck and load £1.2million.