Circadian Rhythm

Anyone feeling a bit off this week? Several people over the last few days have mentioned to me that the time change throws them off each year. I too have experienced this feeling before and wanted to explore some of the reasons why this is. The time change this year came on a saturday night, which means that we 'sprang' forward by one hour. So our bodies woke up feeling like it was 9am on sunday morning but instead on the clock (if you remembered to set it forward) it was 10am. This change was most apparent to my body on this past monday morning when I woke up to go to Crossfit for the 7am class, which has been my routine 3 days a week since December. In the heart of winter, it was dark at 6:30am, which is the time I am getting up and out the door to get to class.  A few weeks before the time change it had started getting light at about 6:30am, the light of each day slowly starting earlier and lasting longer. After the time change this past weekend, it was a bit of jolt to me that after a few weeks of light at 6:30am it is now dark again. How does this change affect our bodies, minds, mental and emotional status?

Just yesterday I was telling my roommate how bad the drivers in Asheville are, IMO. That comment was after I was narrowly missed by a car while I was walking down my street. My roommate is taking a psychology class this semester and said she learned recently that there are more driving accidents following daylight savings time changes. What is that about?

I have heard of circadian rhythm before but wanted to know more in an attempt to explain why we experience the sense of feeling off after day light saving. After some brief research on the internet this is what I came up with. A circadian rhythm is a 24 hour cycle in the biochemical, physiological or behavioral processes of all living things (animals, humans, plants, and even fungi and bacteria). Circadian is derived from the Latin circa meaning around and diem meaning day. While circadian rhythms are inherent to all living things they are also influenced by external cues like daylight. Subterranean animals and organisms for instance do not experience the external cue of daylight and their circadian rhythms are called freerunning because it is based mostly on internal processes like temperature and digestion.

The biological clock in humans is considered to be located within cells in the hypothalamus in the brain. The retina takes in light and the hypothalamus interprets the light and secretes the hormone melatonin in response to it. The secretion of melatonin peaks during the night and ebbs during the day.  Presence of melatonin, either high or low, gives the body information about the length of the night and day. This reaction determines our physiology and our behavior. Another biological marker of the human circadian rhythm is core body temperature, which reaches it highest point at about 5pm.

Overview of biological circadian clock in humans.
Biological clock affects the daily rhythm of many physiological processes. This diagram depicts the circadian patterns typical of someone who rises early in morning, eats lunch around noon, and sleeps at night (10 p.m.). Although circadian rhythms tend to be synchronized with cycles of light and dark, other factors - such as ambient temperature, meal times, stress and exercise - can influence the timing as well.

Studies show that both the amount and quality of the light the retina takes in can affect whether the circadian rhythm is triggered. In fact for the circadian rhythm to be trigger it takes more illumination of light than is found in typical household lighting.

"According to a 2010 study completed by the Lighting Research Center, daylight has a direct effect on circadian rhythms and, consequently, on performance and well-being. The research showed that students who experience disruption in lighting schemes in the morning consequently experience disruption in sleeping patterns. The change in sleeping patterns may lead to negatively impacted student performance and alertness. "

This strongly suggests that the 'off' feeling that many of us experience after the daylight savings time change is based in our biochemistry and physiology. It's not just us imagining something is off, it really is off. Maybe this is why there are more car accidents after the time change - our sleep, coordination, alertness and overall performance is negatively impacted when our circadian rhythms are changed.

Short term disruption in the circadian rhythm can have slight negative impacts, jet lag that travelers experience is an example of this. Typically this is overcome in a few days as people's circadian ryhthm gets re-set. However long term disruption of the circadian rhythm can have negative health consequences and there are several disorders associated with this. (SAD - seasonal affective disorder, sleep disorders like insomnia, and bipolar disorder). This disruption can even have adverse affects on organs other than the brain like the heart.

Perhaps this explains why I felt like I was dragging a bit on monday in Crossfit. We were gifted with the workout Fran bright and early monday morning at 7am. That was my first time doing Fran and after hearing all the stories of how people dread it so much I didn't think it was so bad although it was difficult. Okay I won't blame my monday performance with Fran all on the circadian rhythm thing - I know that I could do it better next time if I just try harder.

I hope you all get your circadians re-set and look forward to springing into spring!