Too tired to be witty
I swear I’m not just pretending to be tired for the purposes of this blog post. I really am inexplicably exhausted — I’ve been getting oodles of sleep lately! So when I was thinking of what to write about today, Davis’ work spontaneously popped into my head. I wish life were always that serendipitous.
Anyway, circadian rhythms are biological processes that naturally follow a 24 hour cycle. “Cycles of light and temperature have had a profound effect on the evolution of life,” Davis said. “Having evolved on a rotating planet gave advantages to having a 24 hour internal clock to anticipate changes in the environment.”
This so-called clock was first detected in 1729, when botanists observed the movement of plant leaves over night and day. In 1938 scientists set up the first circadian rhythm experiment with humans. Subjects lived in Mammoth Cave in Kentucky for extended periods of time with no exposure to natural light. They had control over their own synthetic light sources and without knowing it, maintained their 24 hour day just as if they were living a normal life.
In today’s experiments, lab animals are kept under constant conditions (always light, always dark) and find that their 24 hour behavioral patterns persist. The clock was found to reside in the suprachiasmatic nucleus (SCN) in the hypothalamus, Davis said, which is where the neurons from the eye enter the brain.
You can impair the SCN of a hamster so that his circadian rhythms are all messed up — you know, running on the hamster wheel at all hours of the day or night. But if you transplant a healthy SCN into these guys, their rhythms are completely restored.
In addition to the SCN, research has shown that every cell in the body contains its own mini-clock. Davis’ is now focusing his work in this area, performing stem cell transplants in mice to try and restore function when the rhythms are dysfunctional.
Since people with Alzheimer’s disease tend to have significant problems with their rhythms, Davis said, this kind of work could be very beneficial to human patients.
While I’m pretty sure my exhaustion has nothing to do with wonky circadian rhythms, I am writing this from a windowless office