Why Daylight Saving Time Leaves So Many People Feeling Groggy

When daylight saving time arrives each spring, many people notice they feel groggy, tired, or simply “off.” Losing just one hour of sleep may not sound like much, but even small changes to the body’s internal clock can disrupt sleep patterns and daily routines.

According to sleep medicine expert Sudha Tallavajhula, M.D., professor of neurology at McGovern Medical School, UTHealth Houston, the shift can feel like a form of “forced jet lag” for the entire country. She explains why the time change can be especially difficult for people with sleep disorders and shares practical tips to help your body adjust more smoothly.

Many people feel groggy or “off” after the clock springs forward. What is actually happening in the body when daylight saving time disrupts our sleep schedule?

Sudha Tallavajhula, M.D.: Basically, you are forced to wake up earlier than usual, and for many people that is not an easy thing to do. In theory, you can make up for it by going to sleep earlier than usual. However, the human body is designed in such a way that our circadian cycle is set to something closer to 24.2 hours. Because of this, it is usually easier for us to stay up later than it is to fall asleep earlier than our normal bedtime.

So when daylight saving time begins, many people simply cannot fall asleep earlier the night before. That means they end up getting less sleep than usual. They also miss out on the early morning portion of sleep, which for many people is actually quite deep. That is one of the reasons people wake up feeling groggy.

For people who already struggle with insomnia or irregular sleep, why can daylight saving time be especially challenging?

ST: People with insomnia often struggle with any circumstance that decreases their sleep duration. It could be stress, work obligations or anything that forces them to stay up later than usual.

Many people with sleep disorders are also more vulnerable to changes in their schedule. Think about patients with narcolepsy who need more sleep than others, or people with sleep apnea who do not feel well unless they use their CPAP for a certain number of hours each night.

For all of these individuals, daylight saving time essentially robs them of an hour of sleep. In many ways, it creates a kind of forced jet lag across the entire country. Suddenly the times when you feel hungry, when you want to work out, and when you feel most alert all shift by an hour. For people with vulnerable sleep conditions like insomnia, it can take longer to adjust than it does for others.

You described it as a “forced jet lag,” which is an interesting way to think about it. What are a few simple steps patients can take in the days leading up to the time change to help their body adjust more smoothly?

ST: First, if you can, contact your legislators and ask them to do away with daylight saving time altogether. Sleep medicine scientists and organizations like the American Academy of Sleep Medicine have been advocating for this for years because the time shift is not particularly helpful and may actually be harmful.

As for practical steps people can take, it depends on your body’s natural tendencies. Some people can sleep anywhere at any time, and for them this change may not be a big issue. They may simply be able to fall asleep a little earlier the night before.

But if you have insomnia or what we call delayed sleep phase (often seen in people who are night owls and naturally fall asleep later) then it helps to gradually move your sleep schedule earlier. Try shifting your bedtime and wake time by about 15 to 20 minutes for two to three days before the time change.

If needed, some adults may use a low dose of melatonin (no more than 3 milligrams) to help shift their sleep schedule. The goal is to move the entire sleep window earlier, including both the time you fall asleep and the time you wake up.

Morning sunlight is also extremely important. After waking up, try to get exposure to natural sunlight as soon as possible. Sunlight helps reset the body’s internal clock more effectively than almost anything else.

In addition to adjusting sleep, it can help to shift other daily routines as well. Try moving your meals, workouts and other activity patterns about 15 minutes earlier each day in the days leading up to the time change. Adjusting these routines together can help your body adapt more smoothly.

If someone finds that the time change throws off their sleep for weeks, when should they consider speaking with a doctor about a possible sleep disorder?

ST: Weeks is usually too long. If you think about jet lag, most people recover within about a week, or at most 10 days.

If you are still struggling with sleep beyond that, especially if you feel significantly impaired during the day, it may indicate something more than just difficulty adjusting to the time change. In those cases, it may be helpful to speak with a doctor or sleep specialist. Persistent sleep disruption lasting more than a couple of weeks could signal an underlying sleep disorder that deserves further evaluation.

This transcript was edited for clarity.