What fascinating factoids we picked-up in the first article of the series; as we reviewed what circadian rhythms are, how they work, and the location of the greatest clock known to woman and mankind. Well, now it’s time to discuss the problems caused by circadian rhythm dysfunction.
First, a quick recap. Every living entity has circadian rhythms, including a single cell. To the other extreme, the most significant circadian rhythm humans possess is the one that manages our sleep/wake functioning. And that’s managed by an amazing timing mechanism located in the suprachiasmatic nuclei (SCN) of the brain’s hypothalamus.
See, the SCN receives input regarding “lightness/darkness” from the eye’s retina. The SCN then interprets the information, based upon what’s been received over the past few days; and sends a message to the brain’s pineal gland. And it’s the pineal gland that secretes the hormone, melatonin.
Since melatonin’s job is to induce sleep, it makes sense its secretion would peak at night (dark) and decline during the day (light). So this is about melatonin providing information regarding “night-length.” And it’s all miraculously guided by the rotation of the earth – approximately every 24 hours.
Given the complexities of what we just discussed, it’s pretty safe to say there’s all sorts of room for error. And we know situations and circumstances such as time zone changes, jet lag, medications, working odd shifts, changes in routine, the changing of seasons, pregnancy, and more, can lead to circadian rhythm disorders – jet lag (rapid time zone change syndrome), shift work disorder (I’m suddenly hearing ads on the radio about its treatment), and a multitude of sleep disorders.
But our focus is upon the mood disorders, right?
Okay, it’s known that an insufficient amount of nighttime sleep very often presents before the onset of a depressive episode. And when you toss in the factors I just mentioned – jet lag, working odd shifts, seasonal change, etc. – our circadian rhythm is going to get a little dysfunctional. For example, there’s the possibility of REM sleep occurring earlier in our sleep cycle, resulting in a decrease in the amount of deep sleep. And that can lead to depression.
Another great depressive manifestation of circadian rhythm dysfunction is seasonal affective disorder (SAD). SAD presents in folks who are highly responsive to the total amount of sunlight in their environment. And, of course, when autumn and winter make their annual appearance, and the days become much shorter, depression may be in tow.
Now, bipolar disorder ups the ante just a bit. It’s believed the neurological functioning of those enduring bipolarity is prone to regulatory boo-boos. And many of these errors involve our circadian rhythm. And, of course, the onset of a manic episode, often leading to days without sleep, only makes our rhythm functioning even more dicey. By the way, the efficacy of lithium in the treatment of mania may, in part, be due to its ability to reset our primary internal clock.
I could go on and on; however, I think the point has been made. Circadian rhythm dysfunction can cause problems for anyone. But it’s a major consideration for those enduring mood disorders.
Be sure to join us tomorrow as we tie a bow on the series by discussing what we can do to avoid and treat circadian rhythm challenges.
So how’s the series hitting home thus far? Won’t you comment?