Sleep- an introduction Flashcards
Definition of sleep?
A condition of body and mind which typically recurs for several hours every night, in which the nervous system is inactive, the eyes closed, the postural muscles relaxed, and consciousness practically suspended.
Do you lose perception of senses during sleep?
Our senses continue during sleep but the thalamus blocks sensory signals travelling to cortex where they’re normally consciously received.
Is sleep important?
Main functions of animals are well understood (eating, reproduction etc) but little understood about sleep as they can’t do these essential things when asleep.
‘if sleep doesn’t serve an absolutely vital function, it is the biggest mistake of the evolutionary process ever made’
What is unihemispheric sleep?
Some species have evolved the ability to uncouple the 2 hemispheres of the brain.
Which species have unihemispheric sleep?
Dolphins- maintain life necessary movement in the water.
Birds- 1 hemisphere and corresponding eye is open.
What is the evolutionary theory of sleep?
Inactivity at night is a survival function (being quiet keeps animals safe at night from others who are active).
Reduction of accidents in the dark and reduction of noise.
What is the energy conservation theory of sleep?
This is where the primary function of sleep is to reduce an animal’s energy demand and expenditure (provides inactivity so using less energy).
What is the purpose of hibernation?
In some animals, it acts as a means of conserving energy.
What is the restorative theory of sleep?
-sleep provides opportunity to repair and rejuvenate
-if deprived of sleep, lose immune function, die in weeks
-restorative functions like tissue repair and growth hormone release occur during sleep
-rate of cell division and protein synthesis increase
-restoring physiological functions
-restoring brain systems (REM)
What is the glymphatic system?
This drains toxins from the brain like lymphatic system and is more active during sleep (10-20x).
What do glial cells do during NREM sleep?
Glial cells distributed in brain in NREM sleep to increase space between neurons (allows cerebral spinal fluid to flush out toxins).
What is the Brain Plasticity theory?
Sleep is correlated to changes in structure and organisation of the brain (plasticity), critical for brain development in young people.
Sleep deprivation reduces ability to learn and perform tasks.
What is the mode of memory processing during sleep?
Favours memory consolidation that can’t occur when awake due to environ. demands
Which kinds of sleep are important for memory consolidation?
REM sleep previously thought as most important but now, slow wave sleep (SWS) is vital too
What is a electroencephalogram (EEG)?
This is used to investigate different types of sleep by determining different waveforms.
How is an EEG done?
Electrodes are placed on scalp and record electrical activity of brain. These distinct differences between sleep and awake states and are recorded.
Who developed the first sleep lab?
Kleitman- studied sleep deprivation and REM sleep.
