Lecture 16 - Sleep and Dreaming Flashcards
What are endogenous influences?
Influences originating from inside the body, specifically from the CNS
What are exogenous influences?
Influences originating from outside the body (light, temperature, environment)
What are circannual rhythms?
Yearly rhythms (e.g. birds migratory patterns)
What are circadian rhythms?
Daily rhythms. Regulating the frequency of eating and drinking, bodily temperature, secretion of hormones, urination, and sensitivity to drugs
What is the length of the human circadian clock without any external cues?
24.3hrs
What is a zeitgeber?
Time-giver. A stimulus that resets the circadian rhythm
What is the most critical zeitgeber?
Light
Due to the rise and fall of the sun, who awakens earlier, those in the West or the East?
East
What is jet lag caused by?
Phase-delays (travelling West) or phase-advances (travelling East)
Is it easier to adapt to jet lag when travelling West or East?
West
How does a newborn infant sleep?
18hrs, on/off throughout the day
How does a 16 week old sleep?
15hrs, longer night sleep, regular day naps
How does a 4 year old sleep?
12hrs, long night sleep, afternoon nap
What are examples of biological mechanisms for resetting the circadian rhythm?
Suprachiasmatic Nucleus, genes that produce certain proteins, melatonin levels
What does the suprachiasmatic nucleus do?
Main control centre of circadian rhythms of sleep and temp
How does light reset the suprachiasmatic nucleus?
the retinohypothalamic path - starts from retinal receptors containing photopigment melanopsin
What part does the pineal gland play in circadian rhythms?
secretes melatonin 2-3 hrs before sleep
Does deep sleep increase or decrease over the course of a night?
Decrease
Does REM sleep increase or decrease over the course of a night?
Increase
What occurs during light sleep?
Alpha waves
What occurs during stage 2 sleep?
Sleep spindles and k-complexes
What occurs during deep sleep?
Delta waves
What occurs during REM sleep?
Deep sleep in some ways, but light sleep in others
How long is a sleep cycle?
90 mins
What is the wake centre?
Brain stem (including reticular formation and posterior hypothalamus)
What is the sleep centre?
Anterior hypothalamus
What does the inhibitory neurotransmitter GABA do?
Decrease temp and metabolic rate, decrease stimulation of neurons
What do the excitatory neurotransmitters do? (Acetylcholine, norepinephrine, histamine, orexin)
Increase arousal, maintain wakefulness, increase cortical activity
What are the PGO waves in REM sleep?
Pons-Genticulate-Occipital waves
What is the evolutionary theory of the function of sleep?
Sleep conserves energy - species will sleep different amounts depending on how much they must look for food and watch for predators
What is the repair and restoration theory of the function of sleep?
Sleep enables the body and brain to repair itself
What is the improved cognitive function theory of sleep?
Sleep improves memory, decision making and many other executive functions
What is the activation-synthesis hypothesis of dreaming?
Dreams begin with activity in the pons (PGO - REM sleep) which activates many parts o the cortex (e.g. amygdala). The cortex synthesizes a story from the pattern of activation - normal sensory info cannot compete with the self-generated stimulation and hallucinations result.
What is the neurocognitive hypothesis of dreaming?
Dreams begin with arousing stimuli that are generated within the brain. Stimulation is combined with recent memories and any info the brain is receiving from the senses. Dreams are similar to thinking, just under unusual circumstances/
