3Qs: It may be daylight saving, but we're losing an hour

March 12, 2012 By Casey Bayer
According to biology professor Fred Davis, your body needs time to adjust after losing an hour with daylight saving time this weekend. Credit: Casey Bayer

This weekend we turn the clocks forward an hour for the return of daylight saving time, which means we lose an hour of sleep. We also have to do things an hour earlier than we did before relative to the natural light and dark cycles of the day and relative to our internal body clocks. Biology professor Fred Davis shares how daylight saving time affects our bodies and how simple adjustments can make the transition smoother for us. 

How does turning the clocks forward an hour impact our bodies? 

People who have to get up at a particular clock time will lose an hour of in the morning that cannot be easily made up in the evening by going to bed earlier because their body clock hasn’t adjusted, at least not right away.  

Sleep loss can persist for several days and is the likely cause for a reported increase in traffic accidents after the spring forward. An hour doesn’t seem like a big change but waking up at a different time is a significant transition in our physiology.

People could prepare by getting up a little earlier than normal, something that for many people happens spontaneously in response to the earlier sunrise. After the change, it might help to maximize light exposure in the morning.

Do certain people have a tougher time adjusting to the time change? 

How long it takes for a person to adjust is highly variable from one individual to the next and depends on their current sleeping schedule and exposure to light. Generally that adjustment, doing things at the same social time as before without sleep loss or extra efforts to get up, takes several days to two weeks. Some individuals might never adjust, especially those classified as “owls,” with later bedtimes.

In the fall the end of daylight saving makes it lighter in the morning, but darker earlier at night. In the spring, the time change makes it darker in the morning and lighter later at night — are either of these options better for our sleep cycles or circadian rhythms? 

In our current sleep-deprived society, an extra hour of sleep, as in the fall, is likely to be a beneficial adjustment, and the fall change appears to be easier. Daylight saving time was not implemented for reasons directly related to circadian rhythms, but theoretically the time changes could make sense for our rhythms. 

The start of our “day,” defined as our 16 or so hours of wakefulness, is much more tied to sunrise than the end of our day is tied to sunset. 

As sunrise occurs earlier in the spring, we shift our social day to also begin earlier and vice versa in the fall. This is true for most day-active animals in nature such as songbirds, whose activity begins close to sunrise throughout the year while the end of their day is much more variable. Some researchers have suggested, however, that both changes interfere with the natural progression of adjustments to changing day length.

Explore further: Losing hour over weekend may put heart at risk Monday

Related Stories

Losing hour over weekend may put heart at risk Monday

March 8, 2012
(HealthDay) -- Not only do you lose an hour of sleep after the clocks move ahead to daylight saving time this weekend, you may also be at increased risk for a heart attack, an expert warns.

On March 11, spring forward without losing sleep

March 6, 2012
(Medical Xpress) -- The return of daylight saving time and losing an hour of sleep causes most to cringe at the thought. According to Aparajitha Verma, M.D., medical director of the Sleep Disorders Center at the Methodist ...

Pelayo offers tips to deal with 'spring forward' clock change

March 12, 2012
The change to daylight saving time and other changes to sleep schedules can make it hard to fall or stay asleep. In an effort to help you spring forward and stay on track, Stanford sleep expert Rafael Pelayo, MD, associate ...

Recommended for you

To combat teen smoking, health experts recommend R ratings for movies that depict tobacco use

July 21, 2017
Public health experts have an unusual suggestion for reducing teen smoking: Give just about any movie that depicts tobacco use an automatic R rating.

Opioids and obesity, not 'despair deaths,' raising mortality rates for white Americans

July 20, 2017
Drug-related deaths among middle-aged white men increased more than 25-fold between 1980 and 2014, with the bulk of that spike occurring since the mid-1990s when addictive prescription opioids became broadly available, according ...

Aging Americans enjoy longer life, better health when avoiding three risky behaviors

July 20, 2017
We've heard it before from our doctors and other health experts: Keep your weight down, don't smoke and cut back on the alcohol if you want to live longer.

Parents have critical role in preventing teen drinking

July 20, 2017
Fewer teenagers are drinking alcohol but more needs to be done to curb the drinking habits of Australian school students, based on the findings of the latest study by Adelaide researchers.

Fresh fish oil lowers diabetes risk in rat offspring

July 19, 2017
Fresh fish oil given to overweight pregnant rats prevented their offspring from developing a major diabetes risk factor, Auckland researchers have found.

High-dose vitamin D doesn't appear to reduce the winter sniffles for children

July 18, 2017
Giving children high doses of vitamin D doesn't appear to reduce the winter sniffles, a new study has found.

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.