Circadian Rhythms Flashcards
What is an example of a circadian rhythms?
Sleep/wake cycle.
What is the sleep/wake cycle controlled by and activated?
Light (a exogenous zeitgeber) enters the retina, travels the optic nerve, is detected by the SCN (an endogenous pacemaker), which triggers the pineal gland to lower melatonin levels.
When is the sleep wake cycle the strongest?
2-4 am and 1-3pm. less intense if you have better sleep.
What else is the sleep/wake cycle controlled by?
Homeostatic control. The longer we are awake, the more our homeostatic system tells us we need to sleep, because the more energy we’ve used up.
When is the homeostatic system at it’s peak?
in the evening, when we have used our energy up which leads to a higher need for sleep.
What would happen to our cycles with no external cues?
in absence of external cues, our internal circadian clock will “free-run” at about 24-25 hours (siffre).
How does body temperature affect our sleep wake cycle?
Lowest (36) at 4:30 am and at its highest (38) at 6pm. Sleep occurs when body temp begins to drop, and then rises as you wake up which allows you to be alert when waking up. There’s also a small temp drop at 2-4pm which means people will be tired here too.
