By Lauran Neergaard -
The Associated Press
Most of the United States "advances" daylight saving time on Sunday, and losing that hour of sleep can cause more than just tiredness and a bad mood the next day.
It can also be harmful to your health.
Darker mornings and increased nighttime light throw off the body clock, meaning daylight saving time can cause sleep problems for weeks or longer.
Studies have even found an increase in heart attacks and strokes just after the March time change.
There are ways to make it easier to adapt, such as getting more sun to help reset your circadian rhythm and get healthy sleep.
"Unlike traveling across multiple time zones, the adjustment time it can take is very different for each person," says Eduardo Sánchez, a doctor with the American Heart Association.
"He understands that his body is in transition."
When does daylight saving time start?
Daylight saving time begins Sunday at 2:00 a.m., wiping out an hour of sleep in most of the U.S. The ritual will be reversed on Nov. 3 when the clocks "turn back" at the end of daylight saving time.
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Hawaii and most of Arizona do not make the spring changeover, but instead maintain standard time year-round, as do Puerto Rico, American Samoa, Guam, and the US Virgin Islands.
Around the world, dozens of countries also observe daylight saving time, starting and ending on different dates.
Some people try to prepare for the impact of daylight saving time by going to bed a little earlier two or three nights earlier.
However, one-third of American adults don't get the recommended seven hours of sleep, so catching up can be difficult.
What happens to the brain when you go to bed later?
The brain has a master clock that is adjusted by exposure to sunlight and darkness.
This circadian rhythm is a roughly 24-hour cycle that determines when we are sleepy and when we are most alert.
Patterns change with age, which is one of the reasons why children who wake up early soon become difficult to wake up teenagers.
The morning light restores the rhythm.
At night, levels of a hormone called melatonin begin to increase, causing drowsiness.
Too much light in the afternoon - that extra hour of daylight saving time - delays that increase and the cycle becomes out of sync.
Lack of sleep is linked to heart disease, cognitive decline, obesity, and many other problems.
And the circadian clock not only influences sleep, but also heart rate, blood pressure, stress hormones, and metabolism.
How does the time change affect your health?
Fatal traffic accidents temporarily spike during the first days after the spring time change, according to a study on traffic accident fatalities in the United States.
The risk was highest in the morning, and the researchers attributed this to lack of sleep.
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Then there is the heart connection.
The American Heart Association points to studies that indicate an increase in heart attacks on the Monday after the start of daylight saving time, and in strokes two days later.
Doctors already know that myocardial infarctions, especially serious ones, are a little more common on Mondays in general, and in the morning, when blood is more prone to clotting.
According to Sánchez, it is not clear why the time change aggravates the relationship with Mondays, although it is likely that the sudden circadian alteration aggravates factors such as high blood pressure in people who are already at risk.
Tips for summer time
Go to bed a little earlier on Friday and Saturday nights, and try to get more light in the morning.
Experts advise bringing forward daily routines, such as dinner time or exercising, so that the body begins to adapt.
Afternoon naps and caffeine, as well as the nighttime light from phones and other electronic devices, can make it even more difficult to adjust to an earlier bedtime.
Stay tuned: Some health groups, such as the American Medical Association and the American Academy of Sleep Medicine, have said it's time to do away with daylight savings and that keeping standard time year-round is better suited to the sun and biology human.