6. circadian rhythms Flashcards
What tells the rest of your body what time it is (the master clock of your entire organisms)
Supra chaiasmatic nucleus
how do we call the external things that synchronize the SCN
Zeitgebers
what happens if the SCN is lesioned
the whole body becomes desynchronized (no obvious pattern). You start having bowel movement when you’re asleep, your hormones are expressed at the wrong time. Research with rodents = don’t live really long.
what are the principal zeitgeibers
light is the main one. Than food, activity-rest patterns, social cues (when are you expected to be awake)
melatonin is secreted by which gland?
pineal gland
Around 6 am tons of melatonin AND tons of cortisol. Why are they overlapping like this in the morning?
Preparing you to wake up but melatonin is still keeping you sleepy. for you to be ready to wake of if needed but also able to sleep more
what explains that there’s more melatonin in your body during the winter
SCN will receive information from eye balls (day time or night time). As soon as it receives information that it’s night time, melatonin gets secreted. As soon as it receives the information that it’s day time, it gets suppressed.
So obviously during the winter there’s much more melatonin in your system because it’s dark.
explain how the SCN knows that it’s dark or light
The retino-ganglion cells in your retina communicate with the SCN through the retino-hypothalamic tract
When SCN hears this, communicates with pineal gland to produce more or less melatonine
how are the retino-ganlgion cells in your retina playing a role in melatonine production also called
intrinsicaly photosensitive retinal ganglion cells
Their only job is to react to light and relay that information directly to the brain
what is the role of blue light in melatonin production
Blue light is exactly what those retinal ganglion cells react to, send info to SCN saying stop to produce melatonin.
Block percentage of blue light when you want to be resting.
why are LED light a bad idea
Because they emit a lot of blue light. If you’re exposed, they suppress around 80% of your melatonin.
michel siffre: his circadian rythm in the cave
For about the first month, engenous rythm was about 24 hours
And then became really chaotic. 18-52h. In absence of constant reentrainment, your own circadian system may do other funny things. But will persist for quite a while.
