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Ask any parent about Daylight Savings Time and they’ll groan and roll their eyes. Especially when you have kids, these two times of the year are extremely challenging, to say the least. Sleep schedules are a big deal for parents to get established, so disruptions like these can cause larger stress loads than normal. But many are asking two other very important questions regarding daylight savings time: 1) How does daylight savings time affect your health? and 2) How does it affect your sleep?
To start off with, it can take a week or more for your body to adjust to daylight savings time. In this week, studies have shown 8 or more serious negative affects of daylight savings time:
- Sleep cycles being thrown off,
- which results in higher stress,
- Shifts in eating patterns from hormones being disrupted,
- Higher occurrence of heart attack,
- More traffic accidents,
- And more workplace injuries.
All these add up to some pretty significant shifts in our health that could be avoided. To get a better idea of what this all means and how we should approach it, I asked sleep coach and consultant Sheryl Guloy, PhD for her expert opinion:
Have you heard that there is a discussion on doing away with our annual springing forward to daylight savings time (DST) and falling back to standard time? About a month or so ago, all of this talk reached my neck of the woods, up North…way up to and past the Canadian border, with a beeline to Montreal. The idea of doing away with this time change goes far beyond my city and probably extends or will extend to yours. In fact, this discussion is international in scope and proposals to end this practice is currently ongoing across North America and Europe. It is a hot topic in several states, such as Massachusetts, Washington, Tennessee, and Texas.
While it may seem normal for us to spring forward and to fall back every year, toggling our sleep between standard time and daylight savings time, research on the effects of springing forward reveals just how detrimental to health one hour of sleep loss can be. In Autumn, however, falling back to standard time has been found to result in more positive gains as people’s sleep becomes better (keep this tidbit of information in mind because there’ll be more on this later). Taken altogether, sleep experts, including myself, believe that keeping time consistent throughout the year is best for our health.
Table of Contents
Should Daylight Savings Time be Abolished?
The first reason for keeping our time consistent has to do with sleep loss, which we know negatively affects health, mental health, and performance. When springing forward in springtime, our body misses out on an hour of sleep. The second reason is that our bodies run on a biological clock, entrained to the 24-hour day. It’s from this relationship to the day’s cycle that the biological clock gets its formal name, circadian rhythm. In particular, we have circa, meaning around or approximately, and dies, meaning day, in Latin. The biological clock influences when we become sleepy or become hungry. Specifically, it plays a role in metabolic function and homeostasis as well as in immune response, recovery from mental and physical fatigue, emotional regulation, learning and creativity, and memory consolidation.
Keeping your circadian rhythm consistent is important for the regulation of all of these functions. Research on the effects of switching from standard to daylight savings time has revealed a spike in strokes, heart attacks, and car accidents soon after springing forward. Consequently, policymakers have begun holding discussions on whether the practice of switching between standard and daylight savings times should be abolished, with some places having already chosen to end the practice.
Now, while doing away with the time change is something that is applauded by many researchers and sleep experts, the concern that has arisen in some areas where this policy change is being contemplated has to do with which time would become the default. In particular, the concern has to do with whether an area chooses to select daylight savings time as the “new” standard time.
Why does it matter whether or not we choose daylight savings time?
Well, it matters because our circadian rhythm takes cues from our environment to keep it on track, such as sunlight; temperature change; and eating schedules; among other things. So, this means that our environment and lifestyle affect our biological clock and, consequently, sleep. What happens is that even though we may believe that we should eventually adjust to the time change, the negative effects of springing forward can last throughout the period of daylight savings time for some people.
How the body reacts to daylight savings time
Like I mentioned, not only do our bodies like consistency, but the circadian rhythm is tied to the day, which means that external cues such as daylight and temperature play a role in its regulation. Now, imagine what happens to night owls, for instance, who are already genetically predisposed to going to bed later and are already at greater risk of experiencing sleep deprivation. Imagine what happens to them in the summer when they are exposed to brighter light later in the evening.
Essentially, sunnier evenings delay the circadian rhythm and, hence, the time that people actually fall asleep. Yet, most people still have to wake up at the same time for work throughout the DST period. It’s pretty easy to see how the risk of experiencing sleep loss increases. Right? Remember that night owls will not be the only ones affected. Everyone will be affected but to varying degrees.
Okay, let’s make this even more concrete. What would you expect to happen if we kept standard time versus if we kept savings time?
First, let’s assume a regular 9-to-5 work week, regardless of the time of the year (not factoring in any COVID-19 effects on your work schedule, like working from home). Also, let’s say that you get 7 hours of sleep every night, falling asleep at 11:00 pm and waking up at 6:00 am.
If daylight savings time becomes the new “standard”, how would cities be affected?
To help you see what would happen in very real terms, I’ve created Table 1 to show the effect on sunrise and sunset times in cities across North America, with Houston, Texas, being at the most southerly location, and Edmonton, Alberta, up here in Canada, being at the most northerly location.
Table 1. Standard Time Versus Daylight Savings Time (Sunset/ Sunrise)
In Table 1, I’ve included the actual recorded times for June 21, 2019 in daylight savings time. Notice how late the sun sets in the summertime. This translates into delayed bedtimes because a significant number of people will find it more challenging to fall asleep at earlier times. While the sun sets pretty late in Houston, at 8:25 pm, notice when the sun sets in Seattle and Edmonton. Imagine what it would be like if the sun were to set at around 9:10 pm or 10:07 pm where you live. Personally, I know exactly what it’s like because I used to spend quite some time in Alberta. It feels like it’s only around 5:30 pm or 6:00 pm when it is, in fact, already 9:00 pm at night. No wonder, then, that many do suffer from sleep loss throughout the DST period.
How about during wintertime? What would happen if daylight savings time were to become the “new” standard time? Well, first of all, notice how late the sun would rise in Houston. Basically, the sun’s rays would only begin to appear at around 8:12 am. Now, look at the other cities, where the sun will rise even later. Imagine what it would be like to be in Seattle, where the sun would only rise at 8:54 am. In Edmonton, it would only rise at 9:48 am; that’s only 12 minutes shy of 10:00 am…or mid-morning! Wow. The thing is that bright light in the morning plays a critical role in keeping the circadian rhythm from being delayed too much at night, which is especially important in helping night owls keep their sleep-wake times aligned with the regular 9-to-5 hours that they’ll still be expected to keep.
These examples bring to light some conditions that make daylight savings time problematic if it were to be selected as the default time. Policymakers are essentially proposing that DST be selected as the default when it has been shown to contribute to health, performance, and safety concerns. Unfortunately, daylight savings time is being proposed as the new standard in states like Alabama, Arkansas, Florida, Nevada, Oregon, Tennessee, and Washington. Meanwhile, in Canada, cities like Toronto are also pushing for daylight savings time. In Texas, however, discussions seem to be veering toward keeping standard time as the default, which I believe would be the wiser and healthier choice.
Sheryl Guloy, PhD, is sleep coach/ consultant, researcher, and educator. Her interest in sleep began with her own sleep troubles and her realization that she is a true night owl. She co-founded a sleep initiative, Somnolence+, through which she aims to make sure that more people know about their own sleep and have strategies and tools to help them sleep well.
You can find her blog at: www.sleepwellblog.org
Or on Facebook at: https://www.facebook.com/sleepwellpage
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