Daylight saving time ends next weekend. We tell you how to prepare for the possible effects on your health

The good news: You’ll get a glorious extra hour of sleep. The bad news: for the next few months in the United States it will be very dark.

Daylight saving time ends at 2:00 a.m. (local time) next Sunday, November 3, which means you’ll need to set your clocks back one hour before you go to sleep. This standard time will last until March 9, when we will move forward to spring again with the return of daylight saving time.

That time change can be harder on your body. Darker mornings and lighter nights can throw off the body’s internal clock, making it harder to fall asleep on time for weeks or longer. Studies have even found an increase in heart attacks and strokes just after the March time change.

Falling back to sleep should be easier. But it can still take a while to adjust your sleeping habits, not to mention the inconvenience of leaving work in the dark or trying to exercise when there’s still plenty of light. Some people with seasonal affective disorder, a type of depression usually related to the shorter days and less sunlight of fall and winter, may also have difficulty.

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 standard time better fits the sun and human biology.

Most countries do not apply daylight saving time. In those that do, especially in Europe and North America, the change date varies.

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

This is what you need to know about this ritual that is celebrated twice a year.

How the body reacts to light

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, one reason early wake-ups turn into hard-to-wake 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.

And the circadian clock not only affects sleep, it also influences heart rate, blood pressure, stress hormones, and metabolism.

How do time changes affect sleep?

Even a change in clock time can disrupt sleep schedules because even if clocks change, work and school start times remain the same.

This is a problem because many people are already sleep deprived. About one in three American adults sleeps less than the recommended seven hours a night, and more than half of American teenagers do not sleep the recommended eight hours.

Lack of sleep is linked to heart disease, cognitive decline, obesity, and many other problems.

How to prepare for the time change

Some people try to prepare for the onset of the time change by gradually modifying their sleep schedules in the days before.

There are ways to make it easier to adapt, such as getting more sun to help reset your circadian rhythm and get healthy sleep.

Will the time change in the United States one day be eliminated?

Legislators occasionally propose eliminating the time change. The most recent attempt, a bipartisan bill called the Sunshine Protection Act, proposes making daylight saving time permanent.

Health experts say congressmen are wrong: standard time is what should be permanent.