The twice-a-year shift between Standard Time and Daylight Saving Time has serious effects on our health, safety and performance, at least for several days after the shift. But there’s also a benefit. As we prepare to “fall back” this Saturday night (or “spring forward” in March), let’s look at the effects and why we even have this time change in the first place. Here’s what I found.
The Confusing History
1784: It started with Benjamin Franklin since he’s the one who invented the electric light bulb and first proposed extending the day with artificial lights. So there’s your culprit.
1914: But it was really the German Army during World War I who first changed the clocks – to save money on coal – so they deserve some of the blame too.
1918: Congress enacted the Standard Time Act to establish time zones and daylight saving.
1919: The daylight saving part of the Act was repealed, but some states continued using it.
1919-1966: During this time period that was no federal law regarding Daylight Saving Time.
1966: The Uniform Time Act of 1966 established the system of uniform daylight saving time throughout the United States, beginning on the last Sunday in April and extending through the Last Sunday in October. Individual states, however, could opt-out, and today that includes Hawaii, parts of Arizona, and the U.S. territories of Guam, Puerto Rico, Virgin Islands, and American Samoa.
1974-1975: Congress briefly extended daylight saving time to save energy during the energy crisis. But in modern societies with air conditioning, recent studies have shown that there’s no real energy savings, and in fact usage goes up about 1% when we stay up later.
2005: President George W. Bush signed the Energy Policy Act of 2005 into law. Part of the Act extended daylight saving time from the second Sunday in March to the first Sunday in November, where it remains today. (All of this is quite confusing.)
So what Possible Impact can there be of losing Just One Hour of sleep (or gaining an hour)?
Well, it’s significant:
Heart Attacks. There’s a 24% greater risk of having a heart attack on the Monday after we move the clocks forward. And get this: The risk is 21% LESS on the day after we move the clocks back again. It’s probably because of the relationship between sleep and stress. While stress can make sleep more difficult, less sleep can result in more stress.
Stroke. 8% increased stroke risk the day after springing forward for most people; 23% risk for people over 65 with medical problems. That’s because of the increased stress that 1 hour of lost sleep causes.
Accidents. There are 5%-10% more car accidents on the day after we move the clocks, but for different reasons in different seasons. Accidents during the morning commute rise after we spring forward, simply because people didn’t get enough sleep the night before. But it’s the drive home in the dark that causes accidents when we fall back in November. That’s partially because darkness can trigger production of the hormone Melatonin, which helps the body relax into sleep.
Hunger & Food Cravings. Leptin is the hormone that tells the brain when you’re full, and ghrelin tells your brain it’s time to eat. Just one hour of sleep deprivation has been shown to increase levels of ghrelin, stress hormones, and resistance to insulin, while simultaneously lowering levels of leptin. No wonder being sleepy makes you hungry, craving energy foods with a kick – those foods that are high in sugar & carbohydrates.
Cluster Headaches. They often also occur with travel across time zones, and since the time shift of Daylight Saving Time disrupts the circadian rhythm, it’s just like Jet Lag but without the travel.
Mood Swings. Everyone seems grumpy with an hour less sleep. It affects your appearance too.
But aren’t there Benefits to Daylight Saving Time too?
Once your body adjusts, there truly are benefits of getting more hours of sunlight, but people in the media tend to ignore that.
Attitude. Sunlight increases serotonin, the “happy” hormone, so more sunlight means more serotonin, and more happiness. On the other hand, in the winter or in northern climates when daylight hours are shorter, people can suffer from Seasonal Affective Disorder. SAD is a condition that we can treat with bright artificial lights.
Commerce. With more sunlight in the day, people work later and shop more, and spend more. I heard people mention that as a benefit but with no measured examples.
Health. I didn’t find specific examples, because the media doesn’t talk about it, and studies don’t focus on it, but longer days with more sunlight mean we can be outside and exercise more. We also absorb more vitamin D from that sunlight. That and other factors surely have health benefits that aren’t discussed enough.
So rather than dread Daylight Saving Time, the real question should be, “Why do we fall back in November to Standard Time?” It seems better to just keep Daylight Saving. What do YOU think?
Preparing for, and Recovering from Daylight Savings
You can do the same things to prepare and recover as you would for jet lag, starting with your sleep hygiene. Here’s a short-list of tips to help through the weekend, but we’d like to send you a more comprehensive list.
1. Remember than most adults need 7-9 hours of sleep, so plan accordingly.
2. Leave a few hours between eating and going to sleep
3. In the Spring, sleep in on Sunday and wake when your body tells you to. Yes, you set the clock forward, but do you really need to put on an arm?
4. Dim the lights and quit using electronics an hour before bedtime, because the blue light from screens disrupts your circadian rhythm. Taking a melatonin can help.
5. Get outside into bright sunlight as soon as you wake up since that also helps reset your body clock.
6. SIGN UP for our monthly newsletter, and we’ll send you “70 Tips to Fall Asleep Faster and Stay Asleep Longer.”
Long-term Sleep Deficiency has an Even Greater Health Impact.
Obesity – About 2/3 of American adults are overweight or obese, and about 1/3 of children are overweight. Sleep affects that through the hunger hormones.
Diabetes – About 26M adults & children have diabetes, 79M are pre-diabetic, and sleep deficiency has been shown to increase the diabetes risk 250%.
Immune System – A well-functioning immune systems protects us from colds, flu, and other ailments, but when poor sleep interferes, it fails to do its job. In one study, people who slept less than six hours a night were over four times more likely to catch a cold than those who slept over 7 hours.
Breast Cancer – Women who sleep less than 6 hours a night are 62% more likely to develop breast cancer than those who sleep 7 hours or more. And women who do shift work, such as nurses, have a higher risk of developing breast cancer than those who work during the day. That’s largely because of how light and melatonin regulates circadian rhythms. Sleep can also affect recovery.
Heart Disease – Over 600,000 Americans die each year from heart disease, and sleep deficiency increases the risk by 48%.
Stroke – Each year about 800,000 Americans have a stroke. The one-third of working adults who sleep less than 6 hours a night are 4 times more likely to suffer a stroke.
Depression – A 2007 study of over 10,000 people found that insomnia increased their chance of suffering from depression 5-fold.
Alzheimer’s – Several new research studies have linked poor sleep to the loss of brain tissue, Alzheimer’s disease, and other dementia and neurological disorders, but it’s not yet clear just how much impact it has.
Premature Death – People who sleep less than 6 hours a night are 20% more likely to die in 20 years.
[More detail on these health effects from sleep deficiency will appear later in a white paper, “The Economic Benefits of Population Sleep Wellness,” which I’m working on.]
- The Strange and Surprising History of Daylight Saving Time (National Geographic, with video)
- Daylight Saving Time: Why Does It Exist? It’s Not for Farming! (NY Times, I commented)
- Love it or hate it, here comes Daylight Saving Time (USA Today)
- Daylight saving time can be bad for your health (CNN)
- It’s time to change the clocks: Here are 8 ways to avoid losing sleep this weekend (LA Times, I commented)
- Lawmaker Wants to End Daylight Saving Time in Texas (NBC, I commented)
- A bunch of states want to get rid of daylight saving time. Is your state one of them? (The Washington Post)
- A dozen states are considering getting rid of daylight saving time. Is that a good thing? (Vox)
Fox News (November 1, 2015)
Last Week Tonight with John Oliver (March 8, 2015) – COMEDY CHANNEL
Daylight Saving – THE MOVIE TRAILER
CBS Health Watch (March 7, 2016)
Fox News (March 8, 2015)