BIO PSY CHAP 8

• Endogenous circannual rhythm


  Rhythm generated from within, lasting about a year
• Endogenous circadian rhythms


  Rhythms generated from within, lasting about a day
• Zeitgeber


  Stimulus that resets the circadian rhythm, meaning "time-giver" in German
• Zeitgebers


  • Light
  • Exercise
  • Arousal
  • Meals
  • Temperature
• Social stimuli are ineffective as zeitgebers, unless they induce exercise or other vigorous activity
• The sun controls waking–sleeping schedules even when people follow the same clock time for their work schedule
• Jet lag


  Disruption of circadian rhythms due to crossing time zones
• Phase-delay


  Adjusting to crossing time zones going west
• Phase-advance


  Adjusting to crossing time zones going east
• Cortisol


  Adrenal hormone elevated by stress, damaging neurons in the hippocampus
• Working at night does not reliably change the circadian rhythm because most buildings use artificial lighting which is only moderately effective in resetting the rhythm</b>
• Morning people ("larks")


  Awaken early, reach peak productivity early, become less alert later in the day
• Evening people ("owls")


  Warm up more slowly, reach peak in late afternoon/evening, tolerate staying up all night better
• Social jet lag


  Evening types tend to get lower grades, use more alcohol/risky behaviours due to mismatch with 9-5 schedule
• Morning people report being happier than evening people, possibly due to better alignment with 9-5 schedule
• Suprachiasmatic nucleus (SCN)


  Main driver of sleep/temperature rhythms, located in the hypothalamus
• Retinohypothalamic path


  Branch of optic nerve that alters SCN settings
• Melanopsin


  Photopigment in retinal ganglion cells that respond directly to light
• Period (PER) and timeless (TIM) genes


  Produce proteins that oscillate over a day, promoting sleep/inactivity
• Melatonin


  Hormone released by pineal gland that increases sleepiness (in nocturnal animals, wakefulness)
• Coma


  Extended period of unconsciousness caused by head trauma, stroke, or disease
• Vegetative state


  Alternates between sleep and moderate arousal, no awareness or purposeful behaviour
• Minimally conscious state


  Brief periods of purposeful actions and limited speech comprehension
• Brain death


  No sign of brain activity and no response to any stimulus
• Electroencephalograph (EEG)


  Records electrical potentials of brain cells and fibers
• Polysomnography


  Combination of EEG and eye-movement records during sleep
• Alpha waves


  Characteristic of relaxation, not all wakefulness
• K-complex


  Sharp wave associated with temporary inhibition of neuronal firing
• Sleep spindle


  Burst of 12- to 14-Hz waves, related to memory consolidation
• Slow-wave sleep


  Decreased heart rate, breathing, brain activity, with slow large-amplitude waves
• Paradoxical/REM sleep


  Deep sleep in some ways, light in others, with rapid eye movements
• Reticular formation


  Structure extending from medulla to forebrain, contributes to cortical arousal
• Pontomesencephalon


  Part of reticular formation that contributes to cortical arousal
• Locus coeruleus


  Small structure in pons that emits bursts of impulses in response to meaningful events
• Orexin/Hypocretin


  Peptide neurotransmitter from hypothalamus that enhances arousal and alertness
• Basal forebrain


  Area that provides axons to thalamus and cortex, some increasing wakefulness, others inhibiting it
• Sleep involves decreased sensory input to cortex, with neurons in thalamus becoming hyperpolarized
• Increased GABA activity interferes with information transmission between neurons during sleep, leading to unconsciousness
• Sleepwalking


  Asleep in most of brain but awake in motor cortex, leading to confused behaviour
• Lucid dreaming


  Aware of being asleep and dreaming, with increased activity allowing conscious monitoring and control