the sleep cycle(bio rythms)

Subdecks (2)

Cards (54)

  • Endogenous pacemaker
    Something inside that has the ability to keep time, an internal body clock
  • Exogenous zeitgeber
    An environmental cue from the outside world that keeps our internal body clock on time, also called entrainment
  • Circadian rhythm
    A biological rhythm that lasts around 24 hours
  • The sleep/wake cycle is the most obvious circadian rhythm, but we also have circadian rhythms for releasing hormones and varying body temperature
  • Sleep-wake cycle
    • We have a period of sleep and a period of wakefulness every 24 hours
  • Exogenous zeitgebers (cues like light, clocks, social cues)
    Can conflict with the internal body clock, leading to issues like jetlag
  • Suprachiasmatic nucleus (SCN)

    The endogenous pacemaker for the sleep/wake cycle, also known as the master clock
  • Light detected by the SCN
    Suppresses melatonin production in the pineal gland, making you feel less sleepy
  • The main exogenous zeitgeber for the sleep/wake cycle is the amount of light received in the eyes
  • Social cues like meal times and environmental cues like clocks also work as exogenous zeitgebers
  • Free-running circadian rhythm
    The endogenous biological rhythm maintains itself without entrainment by external cues
  • Studies on free-running circadian rhythm
    • Siffre's 179-day stay in a cave without access to natural light or clocks
    • More recent studies controlling for artificial light use
  • Evidence suggests the SCN is the biological structure responsible for the circadian rhythm in the sleep/wake cycle
  • Disruption to sleep patterns can lead to increased anxiety, decreased alertness, and decreased vigilance
  • Understanding how the sleep-wake cycle is affected by exogenous zeitgebers can help develop treatments for jetlag, improve performance of athletes who travel, and help shift workers be more productive
  • Knowing the circadian rhythms like blood pressure can help with timing drug treatments, benefiting health services
  • Exposure to blue light at night and from personal devices has implications for maintaining healthy sleep
  • Even with social cues, a man blind from birth had a 24.9 hour circadian rhythm, out of sync with the rest of society
  • There is an evolutionary explanation for the day/night cycle of humans and other animals specialized for daytime activity
  • Nocturnal animals like rats have a circadian pacemaker shifted 12 hours, so their wakefulness is at night