Much of the United States “springs forward ” on Sunday , March 9th , for daylight saving time . Worldwide , many other countries also observe daylight saving time , starting and ending on different dates .
The time change can leave people tired and perhaps unhappy the next day . But it also might even harm health . Some studies have found an increase in heart attacks and strokes right after the March time change .
However , there are ways to ease the effects of the time change , including getting more sunshine . The light helps reset your circadian rhythm for healthful sleep .
When does daylight saving time start ?
In the U .S ., daylight saving time begins Sunday at 2 :00 in the morning . The time change will reverse on November 2 when clocks “fall back ” as daylight saving time ends .
The state of Hawaii and most of the state of Arizona do not make the spring change . Those areas remain on standard time along with Puerto Rico , American Samoa , Guam and the U .S . Virgin Islands .
Some people try to prepare for the change to daylight saving time by going to bed a little earlier two or three nights ahead . But with a third of American adults already not getting the suggested seven hours of nightly sleep , catching up can be difficult .
The brain
The brain has a kind of clock that is set by exposure to sunlight and darkness . This clock , known as the circadian rhythm , is on a roughly 24 -hour cycle . It governs when we become sleepy and when we are more wakeful . The rhythms change with age . This is one reason that early -to -rise young children turn into hard -to -wake teenagers .
Morning light resets the rhythm . By evening , levels of a hormone called melatonin begin to increase , leading to tiredness . Too much light in the evening — that extra hour from daylight saving time — delays the melatonin increase . As a result , the cycle gets delayed .
The circadian rhythm affects more than sleep . It also influences heart rate , blood pressure , hormone releases and other systems .
Health effects
Sleep deprivation , or lack of sleep , is linked to heart disease , weight conditions , problems with thinking and remembering , and more .
Deadly car crash numbers increase the first few days after the spring time change , a study of U .S . traffic deaths says . The risk of crashes is highest in the morning , it found . Researchers suggested sleep deprivation might be responsible .
The time change also has a link to the heart . The American Heart Association points to studies that suggest an increase in heart attacks on the Monday after daylight saving time begins , and in strokes for two days afterward .
Doctors already know that heart attacks , especially severe ones , are a bit more common on Mondays generally — and in the morning , when blood is more likely to clot .
Researchers do not know why the time change would add to that Monday connection . But it is possible the sudden circadian change influences other issues such as high blood pressure in people already at risk .
Prepare for daylight saving time
To prepare for daylight saving time , experts offer some advice . Slowly move bedtimes about 15 or 20 minutes earlier for several nights before the time change . Try to rise earlier the next morning , too . Go outside for early morning sunshine the first week of daylight saving time . This is another way to help reset your body’s clock . Start daily activities , like dinner or exercise , a little earlier . This may help tell your body to start getting used to the new conditions , sleep experts suggest .
Daytime sleeping , the drug caffeine and light from phones and other electronic devices can make an earlier bedtime even harder .
End daylight saving time ?
Americans have discussed ending daylight saving time . But so far , no official changes have been made .
Health groups such as the American Medical Association and American Academy of Sleep Medicine believe it is time to end time changes . The groups suggest that staying with standard time year -round works better for human biology and sleep needs .
I’m Caty Weaver .
Lauran Neergaard reported on this story for the Associated Press. John Russell adapted it for VOA Learning English.
circadian rhythm – n. the mental, behavioral, and physical changes a person experiences over a 24-hour period
exposure – n. the condition of being subject to some effect or influence
reverse – v. to undo, to turn about in position or direction
cycle – n. a series of events that take place regularly and return to the same starting point
hormone – n. a product of living cells that circulates in the body and produces an effect on the activity of cells
clot – v. to undergo chemical reactions that result in blood becoming a lump or mass (a clot)
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