Tag Archives: circadian cycle

You and Your Many Clocks

What is it about the Monday following the switch from standard to daylight saving time?

There is a predictable pattern of bad things happening after our “spring forward”: a spike in heart attacks, strokes, and traffic accidents, and even noticeable reduction in worker productivity that are connected to the loss of sleep because “even small changes in sleep could have detrimental effects” including full-blown illnesses.” (Reuters, 2017)

This is because our bodily processes depend upon their precise synchronization with the natural cycles of light and darkness to work properly. Loss of an hour of sleep can disrupt synchronization so that a major disruption can cause serious illness. (Friedman, 2017)

As far back as the 1960s, a German psychiatrist had heard about a woman who was apparently able to keep the demons of her depression at bay by nighttime bicycle rides.  It appeared that going without sleep could “reset” some aspect of the woman’s functioning and relieve the symptoms of depression.

He tested his hunch on a group of his depressed patients by keeping them awake for a single night as a substitute for the nocturnal bicycle ride.

The next day, he was struck by how most of the patients exhibited cheerful optimism rather than their habitual glum weariness.

In another example, physicians in a Milan hospital housing a ward of patients suffering from bi-polar disorder were struck by the fact that patients who occupied rooms that faced east were discharged earlier than those in rooms that faced west. In their reflections about why this was so, the physicians wondered whether the early sun had some therapeutic effect on the patients. (Friedman, 2017)

From ancient times people have observed the effect of day and night on living things, such as flowers opening and closing with sunrise and sunset.

Such observations led 13th century Chinese medical practitioners to connect the cycles of day and night with health and illness.

The actual mechanisms that connect the diurnal cycles to life processes were not discovered until investigators were able to examine biological processes at the molecular level.

The relationship between the organism and the alternation of light and dark based on the solar day is called the circadian cycle, (circa-around; diem-day).

There is now even a whole field of circadian biology whose research has opened new understandings about how we and our environment interact.

The patterns of daylight and darkness are not simply backdrop to our daily lives but  are deeply embedded into our personal biology. In fact, our circadian cycle is tied to the solar day; “it is influenced and kept in check by the daylight cycle.” (Friedman, 2017)

When it gets dark at night a communication channel to the pineal gland is opened activating proteins in the pineal gland that begin to produce melatonin, a hormone that regulates other hormones and is known to help maintain the body’s circadian rhythm. A number of things start to happen, various hormones are activated by the melatonin: your body temperature begins to drop, your kidneys reduce the rate at which they produce urine, and you begin to feel sleepy. (See Melatonin )

Based on this information, it is not difficult to see why the “spring forward”  weekend messes with your circadian cycle. When your alarm goes off on Monday it’s as if you have flown across an entire time zone. You effectively went to sleep in Chicago and woke up in New York, a difference of a whole time zone.  Worse it is probably still be dark,  further confusing your synchronization with the solar day.

Other activities can cause you to get out of sync.

Your television and computer screens emit short-wave length (blue) light that can make it harder to fall asleep.

Shift work especially when the worker is on sometimes during days and then must switch to night work plays havoc and can result in insomnia and even depression. (Moon et al., 2015)

Jet-lag with its fatigue, malaise, poor concentration, and mood changes is the result of flying from one city to another across multiple time zones, leaving your circadian cycle stuck in the time zone you left.  (Friedman, 2017)

So feeling grumpy on the Monday after springing forward is not trivial. The usually temporary malaise is a symptom that several of the many biological clocks that “are believed to exist at all levels of life and play a key role in the maintenance of physiological and behavioral processes” are out of sync.

Chronic disruption of one’s circadian rhythm can cause sleep problems which can adversely affect health. According to research a significant proportion of the adult population does not sleep well and night and has difficulty staying alert during the day…(Harrington, 2010) & (Ray and Reddy, 2016)

There are things you can do to help keep yourself in sync. For example, click here for tips on overcoming jet lag.


Friedman, R. A. (2017c). Yes, Your Sleep Schedule Can Make You Sick. New York Times. Retrieved from https://www.nytimes.com/2017/03/10/opinion/sunday/can-sleep-deprivation-cure-depression.html?ribbon-ad-idx=8&src=trending&module=Ribbon&version=origin&region=Header&action=click&contentCollection=Trending&pgtype=article

Krishnan, H. C., & Lyons, L. C. (2015). Synchrony and desynchrony in circadian clocks: impacts on learning and memory. Learn Mem

Learning & Memory, 22(9), 426-437. doi:10.1101/lm.038877.115

Moon, H. J., Lee, S. H., Lee, H. S., Lee, K.-J., & Kim, J. J. (2015). The association between shift work and depression in hotel workers. Ann Occup Environ Med

Annals of Occupational and Environmental Medicine, 27, 29. doi:10.1186/s40557-015-0081-0

Ray, S., & Reddy, A. B. (2016). Cross‚Äêtalk between circadian clocks, sleep‚Äêwake cycles, and metabolic networks: Dispelling the darkness. Bioessays, 38(4), 394-405. doi:10.1002/bies.201500056

Reuters (2017) Hate daylight saving time? You may have a point, researchers say. Retrieved from http://www.reuters.com/article/us-usa-daylightsaving-idUSKBN16I0S6