Have you heard about the discussion on doing away with our annual springing forward to daylight savings time (DST) and falling back to standard time? This talk about doing away with this time change goes far beyond my city and probably extends or will extend to yours. In fact, this discussion spans across North America and Europe. 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 doing so reveals just how detrimental one hour of sleep loss in spring can be. Falling back to standard time, conversely, results in more positive gains as people’s sleep becomes better.
Sleep experts, myself included, believe that keeping time consistent, all year, is best for our health. Why?
Two things comes into play. The first is sleep loss, which we know negatively affects health, mental health, and performance. When springing forward in the springtime, our body misses out on an hour of sleep and that hour matters. The second is that our bodies run on a biological clock that is entrained to the 24-hour day. In fact, this 24-hour cycle is where your biological clock gets its formal name, circadian rhythm, specifically circa, meaning around or approximately, and dies, meaning day, in Latin. The biological clock is responsible for such things, among others, as when we become sleepy or become hungry. Specifically, it influences learning and creativity, emotional regulation, metabolic function and homeostasis, memory consolidation, immune response, and recovery from mental and physical fatigue. As you can see, keeping your circadian rhythm consistent plays an important role in the regulation of these functions.
So, what happens? When we lose that hour in the spring, we see an increase in heart attacks, strokes, and car accidents.
Now, while I applaud doing away with the time change, I am concerned about how some are going about implementing this change. How come? It has to do with which time will be standardised. In fact, there is a push in many of these areas to make daylight savings time the “new” standard time... very worrisome, indeed.
What’s the big deal with whether we choose daylight savings time or keep the original standard time? Shouldn’t it be okay as long as we keep the time consistent?
Well, it actually does matter because we are not dealing solely with sleep loss but also with the aforementioned circadian rhythm. Keeping your sleep-wake schedules consistent is very important. However, we do not live apart from our environment. Right? Remember, our biological clock is entrained to a 24-hour day. Further, its timing is regulated by external cues that it gets from that very environment, such as sunlight, temperature change, eating schedules, etc.
What this means is that our environment and lifestyle affect our biological clock and sleep.
So, it is not surprising that, even if we think that the body should adjust to the change, research reveals that the negative impact of springing forward can last throughout the period of daylight savings time for some people.
So, let’s break down why:
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 like me, for instance. We are already genetically predisposed to going to bed later and are already at greater risk of experiencing sleep deprivation. Imagine what we have to deal with when we are exposed to brighter light later into the evening, as is the case in the summer.
In effect, when we are exposed to brighter light later in the evening, our circadian rhythm is delayed even more. Hence, we are unable to fall asleep until even later in the night or in the early morning. Unfortunately, many of us still have to wake up at the same time every day throughout the daylight savings time period. Do you see how the risk of experiencing sleep loss increases? Now, night owls will not be the only ones affected. Everyone will be affected but to varying degrees.
However, let’s make this even more concrete for you: 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). Let’s also say that you obtain 7 hours of sleep every night because you fall asleep at 11:00 pm and wake 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 the following table to illustrate the issue with daylight savings time. I’ve included cities across North America, with Houston, Texas, as the one furthest south and Edmonton, Alberta, as the one furthest north.
Table 1. Standard Time versus Daylight Savings Time (Sunset/ Sunrise in Five Cities)
In Table 1, I’ve included the actual recorded times for June 21, 2019 in daylight savings time. Notice how very late the sun sets in the summer. This translates into delayed bedtimes because a significant number of people will find it more challenging to fall asleep earlier. While the sun sets pretty late in Houston, at 8:25 pm, notice the times in Seattle and Edmonton. Imagine what it would be like if the sun were only to set at around 9:10 pm or 10:07 pm. I, for one, know exactly what that’s like because I have spent quite a bit of time in Alberta. It confuses your system because it only feels like the late afternoon or early evening when it is, in fact, already 9:00 pm at night. No wonder, then, that many people suffer from the effects of sleep loss throughout the DST period.
Now, what would happen in the winter if daylight savings time were to become the default? Notice, now, how late the sun would rise in Houston. Basically, it would be dark until 8:12 am in the winter. However, look at the rest of the cities. Notice how the sun will rise even later. Imagine that in Seattle, the sun would only rise at 8:54 am. In Edmonton, it would only rise at 9:48 am … that’s practically mid-morning. The critical thing to remember is that bright light in the morning is essential in keeping the circadian rhythm from being delayed too much at night, especially for night owls, who will be hit especially hard, once again.
These examples bring to light the conditions that make daylight savings time problematic if it were to be selected as our default time. Essentially, policymakers are proposing that DST be selected as the default when it is known to contribute to health, safety, and performance issues. For these reasons, it is almost as though we would be taking a step in the right direction in doing away with the time change, but we would be taking two steps back if we select DST as our default time.
So, now you know some of the issues that should be discussed when moving this item forward in the agenda. Unfortunately, in Alabama, Arkansas, Florida, Nevada, Oregon, Tennessee, and Washington and in cities like Toronto, the push is for daylight savings time as default. In Texas, however, the push is for keeping the default as standard time, which would be the wiser and healthier choice.