Circadian Rhythm Disruptions in the Older Adult

Melatonin is o-methylated and acetylated serotonin made in the pineal gland in vertebrates as a result of stimulation by norepinephrine.1 From the pineal gland, melatonin is secreted into the cerebrospinal fluid, and then to the hypothalamus where the suprachiasmatic nucleus, or the body clock, is located. Thus, blood levels of melatonin underrepresent the actual levels reaching receptors in the hypothalamus.2

Light regulates the suprachiasmatic nucleus, which, in turn, acts as a pacemaker to regulate the circadian rhythms including temperature, cortisol levels, sleep propensity, an...