Circadian rhythms include:
a. sleep
b. temperature
c. eating
d. all of the above
ans:
All of the above
The circadian clock drives many rhythms including behavior, core body temperature, sleep, eating, drinking, and hormonal levels. One such circadian-regulated hormone is the indolamine, melatonin. Melatonin synthesis is controlled through a multisynaptic pathway from the CNS to the pineal gland. Serum levels of melatonin become elevated at night and return
to baseline during the day. Light suppresses elevated melatonin levels, immediately decreasing them to baseline levels. Light also shifts the phase of circadian rhythms of melatonin synthesis. Because melatonin can be assayed easily, it provides a convenient window into the state of the circadian pacemaker.