Good news: You’ll get a great extra hour of sleep. The downside: It will be dark as a pocket in the afternoon in the US for the next few months

Daylight saving time ends next Sunday, November 3rd at 2am local timeThis means you should set your clock back an hour before going to bed. Standard time will last until March 9, when we will “move forward” again with a return to daylight saving time.

This spring time change may be harder on your body. Darker mornings and lighter evenings can disrupt your internal body clock, making it difficult to fall asleep on time for weeks or longer. Studies even found an increase in heart attacks and strokes immediately following the time change in March.

It should be easier to “step back”. However, it may still take some time to adjust your sleep habits; not to mention the downsides of leaving work in the dark or trying to exercise while there’s still enough light. Some people may also have problems with seasonal affective disorder, a type of depression linked to shorter days and less sunlight, usually in the fall and winter.

Some health groups, including the American Medical Association and the American Academy of Sleep Medicine, have said it is time to eliminate time shifts and that sticking to standard time better accommodates the sun and human biology.

Most countries do not observe daylight saving time. For those who do this (mostly in Europe and North America), the replacement date for the watches varies.

Two states – Arizona and Hawaii – do not change and remain on standard time.

Here’s what you need to know about the twice-yearly ritual.

How the body responds to light

The brain has a master clock that is set by exposure to sunlight and darkness. This circadian rhythm is a roughly 24-hour cycle that determines when we will be sleepy and when we will be more alert. Patterns change with age; This is one reason why young people who wake up early turn into young people who are difficult to wake up.

Morning light resets the rhythm. Towards the evening, levels of the hormone called melatonin begin to increase and trigger drowsiness. Too much light in the evening (an extra hour due to daylight saving) delays this oscillation and desynchronizes the cycle.

And this circadian clock affects more than just sleep; It also affects things like heart rate, blood pressure, stress hormones, and metabolism.

How do time changes affect sleep?

Even a one-hour change in time can disrupt sleep schedules; because even if the hours change, work and school start times remain the same.

This is a problem because many people are already sleep deprived. Nearly 1 in 3 U.S. adults sleep more than the recommended seven hours a night, and more than half of U.S. teens don’t get more than the recommended eight hours a night on weeknights.

Sleep deprivation is linked to heart disease, cognitive decline, obesity and many other problems.

How to prepare for a time change

Some people try to prepare for the shock of the time change by changing their bed times little by little in the days before the change. There are ways to make it easier to adjust, including getting more sunlight to help reset your circadian rhythm for healthy sleep.

Will the USA survive the time change?

Lawmakers occasionally propose getting rid of the time change altogether. The most prominent recent initiative, a bipartisan bill called the Sunshine Protection Act, proposes making daylight saving time permanent. Health experts say lawmakers are backing down and standard time should be made permanent.

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The Associated Press Health and Science Department receives support from the Howard Hughes Medical Institute’s Science and Education Media Group. AP is solely responsible for all content.