Your energy levels change throughout the day thanks to your circadian rhythm. It’s your internal 24-hour clock that regularly switches between alert and sleepy. Each person’s clock varies slightly creating morning people, night owls, and everyone in between. Circadian rhythm is found in almost every living thing on earth, even plants!

While the day/night, light/dark cycle of the earth turning plays a huge role in setting the clock, circadian rhythm actually runs in the background within all of us. This is easily illustrated in a study from back in the 1700s. A French scientist, de Mairan, described the daily leaf movements of a plant. He observed that the daily raising and lowering of the leaves continued even when the plant was placed in an interior room and thus was not exposed to sunlight. These findings suggest that the movements rely on something more than a simple response to the sun. They’re controlled by an internal clock.

In terms of health, research is showing circadian rhythms influence sleep-wake cycles, hormone release, eating habits and digestion, body temperature, and many other functions. This means a disruption in the normal cycle can have a huge impact on your overall health as irregular rhythms have been linked to various chronic health conditions, such as sleep disorders, obesity, diabetes, depression, bipolar disorder, and seasonal affective disorder.

Disrupting the clock

DST disrupts circadian rhythm

(A) Half-monthly averages of midsleep times and of wake-up times are plotted. DST periods are indicated by the open boxes and their transitions by dashed horizontal lines. Dawn times are shown as a gray to white border. Sleep times track dawn under standard time. In DST mid-sleep is scattered around 3:30 (wake-up times around 7:40) without much regard for the dawn. (B) Seasonal changes in sleep duration result in about 20 min more sleep in winter than in summer.

A normal circadian rhythm wakes us around the rising of the sun. This synchronizes us to the environment and adapts fairly well with the shortening and lengthening of the days throughout the year.

This blog is being written a few days after springing forward for daylight saving time (DST) with the author on their third cup of coffee. For me and many others, time changes are a major disruption of the circadian rhythm. And the research shows it. The leap forward has been indicated in problems like heart attackstraffic accidents, and work place injuries in the days and weeks to follow the change.

Daylight saving time only represents a change in our social clock, not our biological ones. We all agree to wake up an hour earlier and change routines. But our circadian rhythms never fully adapt to the change before we fall back. A study showed that sleep times decreased by about 20 minutes in summer DST compared to winter. It also showed that waking tracked with the dawn in standard time but remained disrupted during DST.

While falling back may help restore our circadian rhythm it’s not without some health issues. Studies have found a link between depression and suicide when the clocks turn back.

History and politics of DST

For almost a century, countries have been regularly springing forward and falling back. It started largely as an effort to conserve energy in times of war. It also has the benefit of shifting daylight hours to times later in the evening for more recreation after work hours. This also helps stimulate economies because with “extra daylight” people shop more or purchase items for leisure.

But in more recent years, people have begun to question the practice. Is the disruption of our circadian rhythm worth it? Studies have been largely inconclusive with the energy savings. Nationwide it might lower consumption of electricity by 0.5%, but other regional studies show increase consumption by around 1%. All kinds of things may contribute, like our use of air conditioners, but it’s not reliably studied.

While history and politics are not topics we usually address here, it may be important to consider for the health of many people in the United States. It may be beneficial to end DST, but many still enjoy the additional leisure time in the evenings. We have some examples of states that don’t change; Arizona and Hawaii. But we may have a new option. California is considering not falling back and remaining an hour ahead. It is unknown what this might mean for circadian rhythms but it is worth further study.

Resting the Clock

Regardless of the politics, we still have to deal with disruption to our circadian rhythm. While our internal clock can run without input, it does take cues from our environment. Here are some things you can do to help rest your clock and get back in a healthy cycle.

  • Embrace the light. Upon waking, introduce both artificial and sunlight if possible. Light is the main driver of the circadian rhythm so embrace it.
  • Eat a healthy breakfast. Food tells the body it’s time to wake up and start the day. Skipping it can cause a lag in your normal cycle.
  • Go for a morning walk. Exercise, along with the early morning sun, really gets the blood flowing.
  • Get adequate sleep. Darkness and sleeping are also important for our internal clock, about as much as light. Make sure you’re getting a healthy amount of sleep.

These should hopefully get you and your circadian rhythm going. If you’re still struggling with the time change, see your health care provider. They may be able to assist in resting the clock or find a different reason for your symptoms.