Saturday, November 8, 2014

Daylight Saving Time is a good thing and you should stop complaining about it.

Like saturated fat, rock and roll music, and Saturday morning cartoons, Daylight Saving Time (DST) has been blamed for many of the world’s ills and the eventual downfall of western civilization. Take a look at its Wikipedia page: It’s been linked to increased heart attacks and suicides! I’m highly doubtful that these claims are correct, but I’m also skeptical of many of the alleged benefits, too. It probably won’t save us much energy or significantly improve public safety. So why should we keep setting our clocks back and forward?!

Circadian rhythms and you

This is where the greatest misunderstanding about DST occurs. The sudden loss (or gain) of an hour may cause a “jet lag” effect on sleep. This is understandable since most people base their day on the clock, not the sun. If you wake up by alarm clock the same time every day, then the shift caused by the DST change will disrupt your typical sleep schedule. Okay, so get rid of DST and our sleep patterns will be healthy again, right? Not so fast...

Circadian rhythms are mostly driven by (blue) light exposure. Those of us who live further away from the equator have greatly varying amounts of sunlight depending on the time of year. Starting with the day of least sunlight, the first day of winter, the amount of sunlight exposure increases each day. Sunrise happens a little earlier and sunset a little later. This increase keeps on going until it hits a maximum on the first day of summer. The sun rises the earliest and sets the latest for the entire year.

Here’s a chart showing the rise and fall of daily sunlight for where I live:

Sunrise, sunset and time of light for Central Islip, NY.
Notice that the amount of daylight has nothing to do with DST. This misunderstanding is why most assumptions about improved energy savings are based on faulty logic.

Our ancestors used the sun to signal the beginning and end of the day. Starting in winter, each day they got up a little earlier and went to bed a little later until summer when the process reversed. However, modern humans now have precision timekeeping devices called clocks. People run their daily lives by the exact time-of-day instead of the variable sunrise. This is inherently unnatural and can be unhealthy. DST shifts may noticeably exacerbate this problem, but are not the underlying cause of it.

Now that we know the use of clocks to determine the start and end of the day are a root cause of circadian mismatch, what’s the solution? Well, it’s pretty simple: wake up with the sun like our ancestors did. Keep the windows in your bedroom uncovered and let the sun be your alarm clock. If this is unfeasible, get an alarm clock that can wake you based on your location’s sunrise rather than on a fixed time of day.


Waking up with the sun may help your body’s circadian rhythm, but it may not be very convenient for living in a modern world. Work, school, stores, banks, etc. are still on a regimented 9-5 schedule. The sun will rise extremely early in the summertime and set later in the evening. This creates a discontinuity of your spare time. You get a little extra before work (when it’s least convenient) and a little extra after. If only we could all start our workday earlier in the summer months and later in the winter months. Let’s all agree to change our work hours from 9-5 to 8-4 in the summer and then back as we get closer to winter. We still wake up with the sun, but we would in effect shift our work schedule so that our free-time is mostly later in the day. Congratulations; you just reinvented DST...poorly. Now instead of turning the clock back or forward, you have to add or subtract to the operating hours of every place you do business with twice a year.

Justification for Daylight Saving Time to the effect that it will help people rise with the sun.
Justification for Daylight Saving Time to the effect that it will help people rise with the sun.

“Daylight saving time.” Wikipedia, The Free Encyclopedia. Wikimedia Foundation, Inc. 8 Nov. 2014. Web.

Here’s a walkthrough of the above chart:
The biological basis for “Spring-Forward/Fall-Back”: The “Spring-Forward/Fall-Back” adjustment is explained as a correction of rigid mechanical time toward flexible natural time so that clock time shifts toward the natural synchronization of our body clocks to the sunrise as it changes throughout the seasons. The natural cycle shown in Chart #2 is more closely matched by Chart #4 (with the Spring-Forward/Fall-Back shift) rather than the unshifted Chart #3. Natural time is called flexible (where “the hours bend”) because hours historically were divisions of time from sunrise to sunset. Sunrise to noon was divided equally, as was noon to sunset. Also sunset to midnight and midnight to sunrise. So Summer had longer daytime hours and short nighttime hours. Winter had shorter day-hours with longer night-hours.


Don’t blame DST for the cock-up of our circadian rhythms. Used correctly, DST helps our modern clockwork-driven world adjust to our ancestral sleep and wake patterns.

DST motivator.

Alternatively, you can drop out of the rat race and live ancestrally.

Bill's tweet.

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