Spring forward, fall back — In Tennessee, we take for granted that we will change our clocks twice a year. But does observing daylight saving time (DST) actually affect our health?
What is daylight saving time?
Daylight saving time is the practice of setting the clock forward one hour each spring. That way during the warmer part of the year, evenings have more daylight and mornings have less.
While fewer than half of the countries in the world participate in DST, since 1966 every U.S. state has observed it except Arizona, Hawaii and the territory of Puerto Rico.
When is daylight saving time?
Daylight saving time:
- Goes into effect the second Sunday in March and
- Ends the first Sunday in November.
It lasts for about 238 days, or about 65% of the year.
Where does daylight saving time come from?
DST was originally invented in Germany as a way to save energy during World War I, though most studies indicate it’s probably not saving us much energy now. There was also a popular myth that DST started because farmers wanted more daytime in their fields, however the opposite was actually true; Dairy farmers fought it because it was difficult to get cows to adapt a new milking schedule.
Does daylight saving time affect your health?
Yes, especially in the short term. In Tennessee, we see more sunlight but may get less sleep when the time changes. In some areas, DST can also push back sunrise as late as 8:30 a.m., which can make it difficult to get up in the morning. Our bodies are sensitive to schedule changes, and that can lead to problems adjusting.
Heart attack and stroke
Heart attacks increase up to 25% the Monday after daylight saving time in March, and the risk of stroke is 8% higher. In November when the clock falls back, heart attack visits drop 21% as people get an extra hour of sleep.
People who suffer regular headaches may see an increase in frequency after the time change because of sleep deprivation.
In the weeks it may take for our bodies to adjust, we are more prone to deadly driving mistakes. Researchers estimate that car crashes related to DST have cost up to 30 people their lives over a decade.
Injuries and suicide
Does daylight saving time have long-lasting effects?
All of the consequences above are connected to the event of the time change, not to the quality of life connected to how much daylight we get each day. That effect, however, is often the most substantial long-term. With fewer daylight hours later in the day, some people report an increase in fatigue, depression or even seasonal affective disorder (SAD).
Adversaries of DST argue that because the practice effectively “steals” an hour of daylight from the afternoon and moves it to the morning — a time when most people are indoors anyway — it negatively affects quality of life. Some lawmakers in Tennessee have argued abolishing it would mean more daylight year-round, which they say could decrease electricity use in the evening (though probably not by much) and allow people to spend more hours out in the local economy at night. If you think you may suffer from SAD, learn more about treatments such as light therapy here.