Navigate

November 3, 2011

Goodbye, sun. Hello, confused suprachiasmatic nucleus!

In my book, Ben Franklin is the man. An expert swimmer, self-taught pentaglot, and inventor of the "glass harmonica," he was also among the first to suggest the notion of Daylight Savings Time. A 1784 essay by Franklin suggested that an extra hour of daylight in the evening would save on candles.

I love that extra hour. As a kid during the summertime, it meant my brother and I could play our aptly-named "Kick the Ball" game in the yard after dinner. Nowadays, it means I can see where I'm going when I walk home from an afternoon in lab.

The end of Daylight Savings Time (which occurs at 2 a.m. this Sunday) means an end to all that, and the beginning of—well, winter. And winter is...cold. So very cold...

For most of us, changing our clocks back an hour is no big deal—in fact, it has its perks over "spring forward" in that we get an extra hour of sleep. But for others, changing the time can have a big impact on our circadian rhythm.

That's right—our brains have their own predetermined 24-hour cycle, and the study of chronobiology is serious business. On a day-to-day basis, you can alter your sunlight exposure or sleeping patterns, but—as you've probably experienced—at a cost. In reality, your confused brain prefers to keep its own schedule, thank you very much. Some research suggests that setting our clocks an hour back this Sunday can take between two and three weeks to fully adjust.

Luckily, our circadian rhythms aren't completely set in stone. Interestingly, research shows that mammals with prolonged exposure to darkness can eventually learn to function with a freerunning rhythm. On the opposite end of that, those funny little blind cave animals can actually maintain their rhythm without any external cues. So why are humans so wimpy when it comes to getting a few extra ZZZs?


The retinas in our eyes contain a type of specialized cell called a ganglion cell, which contain the photopigment melanopsin. When we are exposed to sunlight, melanopsin signals follow a pathway leading to the suprachiasmatic nucleus (SCN). The SCN is a pair of cells located in the hypothalamus, a region in the brain responsible for regulating many important biological functions in our bodies.

The SCN is pretty smart, you see—it takes this sunlight information and interprets it before passing it onto the pineal gland, a tiny structure responsible for melatonin secretion. Melatonin peaks at night and wears off during the day. This, folks, is the mighty little molecule responsible for our circadian rhythm:

If you find yourself in the throes of non-travel-induced jetlag in the coming weeks, there are a few things that doctors recommend trying:

Go to bed earlier. Going to bed a little earlier (15 minutes) these next few nights will give you some additional time to adjust for the bigger change on the way.

Take over-the-counter melatonin. Melatonin can be purchased at vitamin and health food stores, and can help realign your body's rhythm if you find yourself suffering from insomnia.

Don't alter your schedule just because the sun decided to. When it's dark, it takes much more effort and determination to get those chores done or drag yourself to the gym. Figure out a plan in advance, and stick with it.

Complain to your rental office about your neighborhood's poor lighting. Oh, wait, sorry—that last one was a note to myself.

Photos courtesy U.S. Recall News, Wikipedia, and HBC Protocols.

Moore RY (1997). Circadian rhythms: basic neurobiology and clinical applications. Annual review of medicine, 48, 253-66 PMID: 9046960

1 comment:

  1. Except that the children don't adjust their clock as well as us. Now, they wake up around 6am rather than 7am... You can only take advantage of this extra hour of sleep when you don't have children... It probably does not save energy anymore but it forces all the children to change their schedule twice a year....

    ReplyDelete