The good news: you’ll get a good hour of extra sleep. The bad: It will be pitch black in the late afternoon for the next few months in the United States

Daylight saving time ends at 2 a.m. on Sunday, November 3, which means you need to set your clock back an hour before you go to bed. Standard Time will last until March 9, when we will “forward” again. with the return of summer time.

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

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

Some health groups, including the American Medical Association and the American Academy of Sleep Medicine, have said it’s time to do away with timers and that sticking to standard time better aligns with the sun — and human biology .

Most countries do not observe daylight saving time. For those who do – mainly in Europe and North America – the date the clocks are changed varies.

Two states – Arizona and Hawaii – are not changing and staying on standard time.

Here’s what you need to know about the biannual ritual.

How the body reacts to light

The brain has a master clock that is set based on exposure to sunlight and darkness. This circadian rhythm is an approximately 24-hour cycle that determines when we become sleepy and when we are more alert. Patterns change with age, one reason why young people who mature early become difficult-to-wake teenagers.

Morning light resets the rhythm. In the evening, levels of a hormone called melatonin begin to increase, triggering sleepiness. Too much light in the evening – that extra hour compared to daylight saving time – delays this surge and the cycle becomes out of sync.

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

How do time changes affect sleep?

Even a time change can disrupt sleep schedules, because even though the 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 sleep less than the recommended seven hours a night, and more than half of American teens don’t get the recommended eight hours on weeknights.

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 a time change by gradually changing their bedtimes in the days leading up to the change. There are ways to make adaptation easier, including getting more sunlight to help you reset your circadian rhythm and enjoy healthy sleep.

Will the United States ever get rid of the time change?

Lawmakers sometimes propose doing away with the time change altogether. The most prominent recent attempt, a now-blocked bipartisan bill called Sun Protection Actproposes to perpetuate summer time. Health experts say lawmakers have taken things the other way: Standard time should become permanent.