Sleep Flashcards
Why does sleep occur?
Occurs due to active inhibitory process that originates in the pons
What effect does destruction of the at the level of the mid-pons?
Creates a brain that never sleeps.
Where specifically in the pons is it suggested that sleep comes from?
Reticular formation - actively sends inhibitory impulses to the cortex to induce sleep
What functions is the reticular formation associated with?
Consciousness with higher centre connections
How is the hypothalamus involved in sleep?
- Suprachiasmic nuclei (SCN) - stimulates release of melatonin from pineal gland
- Decrease in secretion of excitatory neurotransmitter orexin (hyposecretin)
What two techniques/investigations are used assess levels of consciousness?
- Behaviour and cognition
2. EEG
What two things are measurable about brain activity in EEGs?
Frequency and amplitude
What types of EEG waves are there?
Alpha, Beta, Theta, Delta
How are alpha waves characterised?
High amplitude and high frequency
How are beta waves characterised?
Low amplitude and high frequency (asynchronous)
How are theta waves characterised?
Variable amplitude and low frequency
How are delta waves characterised?
High amplitude and very low frequency
Outline the four stages of sleep
- Slow wave, non-REM, S-sleep, slow eye movements
- Eye movements stop, sleep spindles occur
- Very slow delta waves
- Deep sleep (sleep walking/talking occurs)
What is REM-sleep?
Characterised by fast waves, typical to the waking state
What are the characteristics of deep sleep?
First few hours of sleep there is a decrease in blood pressure, respiration rate and metabolism
What are the characteristics of REM-sleep?
Dreams occur, brain activity similar to the waking stake
What are the symptoms of sleep deprivation?
Impaired cognitive function
Sluggishness
Irritability
Psychosis
What are the purposes of sleep?
Neuronal plasticity
Learning and memory
Cognition
Clearance of waste produced by the CNS
What is insomnia?
Chronic inability to obtain the necessary amount of sleep over a prolonged period of time
What are the two types of insomnia?
Chronic (idiopathic) and temporary (linked to psychological stress)
What is somnambulism?
Sleep walking - can walk around with eyes open, avoid objects but have no memory of it
What is narcolepsy?
Patients directly enter REM-sleep intermittently due to a defunct orexin release system
