Sleep and dreams Flashcards
How do we define sleep
Sleep is a reversible state of reduced awareness of and responsiveness to the environment.
NREM
Non-rapid eye movement
Rem
Rapid eye movement
what biological rhythm is Circadian?
around a day, 24 hours internally.
• e.g. the sleep-wake cycle.
what biological rhythm is Ultradian?
less than a day, cycles that occur within a day
• e.g. temperature fluctuations, cognitive vigilance, sleep stages and hormonal.
what biological rhythm is Infradian?
more than a day
• e.g. menstrual cycle 28 days.
SCN
Suprachiasmatic Nucleus
How does the SCN work ?
By using information obtained by the retina but the retinohypothalamic path, and by the clock and bmal1 cells creating cry and per which. This process takes 24hours and will block it while cry and per are active
(Stanewsky, 2003)
• PER gene for the biological clock, was involved in all three mutations of fly suggesting that flys may have a sense of time
(King & Takahashi, 2000)
• Mammals also carry the same gene, but it is referred to as the clock gene
what happens if we Transect optic nerve before optic chiasm?
no light/dark entrainment
Transect optic nerve after optic chiasm?
preserved light/dark entrainment
what does the SCN control
Alert or awareness is controlled by the SCN
what influences the SCN
influenced by light and other ‘zeitgebers’ – ‘time givers’, including social cues, noise, temperature
No zeitgebers
However, without zeitgebers, organisms can adapt (e.g. blind mole rats) – the internal state used
How does light effect the Scn
Light suppresses SCN firing and this, in turn, suppresses pineal production of melatonin
how much sleep do people need ?
Newborn up to 18 hours 1–12 months 14–18 hours 1–3 years 12–15 hours 3–5 years 11–13 hours 5–12 years 9–11 hours Adolescents 9–10 hours Adults, including elderly 7–8 (+) hours Pregnant women 8 (+) hours
How can we measure sleep ?
EEG
EOG
EMG
Actigraphy
EEG
Electroencephalogram (EEG)
• Measures electrical activity of the brain
EOG
Electrooculogram (EOG)
• Measures eye movements
EMG
Electromyogram (EMG)
• Measures electrical activity of the muscles
Actigraphy
Actigraphy
• sensor measures gross motor activity – crude measure such as fitbit
Stage 1
refers to the transition of the brain from alpha waves to theta waves (theta activity)
Stage 2
no eye movement or theta activity. There are sleep spindles, 1-2 second bursts of 12-14 Hz activity, and K complexes
Stage 3
very slow brain waves (delta waves) that have a frequency of 1-4Hz
Stage 4
delta waves predominate for a deeper level of sleep
REM (‘paradoxical’) sleep
similar to wakefulness in terms of brain waves, blood pressure, temperature. Where dreams occur. Between 3-5 each night.
