It’s that time again, at least here in the US. I rant about DST because there is something fundamentally wrong with how we do it. And proposed solutions are even worse. Nothing infuriates me quite like the stupidity of fixing a mistake with an even bigger mistake. In order to make the choices more clear, I analyzed the badness of each DST policy and put a number on it. (Details at the end.)
BLUF –If you really must live by the clock rather than getting up naturally, then the optimal DST policy is to spring forward in early April and fall back in mid-September. This is provably better than both permanent DST and permanent standard time.
Status quo (333 stupidity points)
Currently in the US, DST starts on the second Sunday in March and ends on first Sunday in November. The “spring forward” change creates several weeks of misery each year, including a measurable number of excess deaths, injuries and economic losses. This brilliant system was imposed by congress in 2005, ostensibly to save more energy than the previous DST schedule. Go figure.
In the plot below, the blue curve is time of sunrise throughout the year in Washington, DC. (Astronomical “sunrise” is when the first rays of direct sunlight reach your point on Earth.) The red line is get up time for a typical work day. When the red line is below the blue line, you’re getting up before sunrise. Each hour you get up before sunrise costs 2 stupidity points. When the red line is above the blue line, you are sleeping in or otherwise idling. This is the daylight that DST is supposed to save. Each hour of idling costs 1 stupidity point.
1986 DST schedule (301 stupidity points)
From the first Sunday in April to the last Sunday in October.
Optimal DST (256 stupidity points)
From first Sunday in April to third Sunday in September.
I played around with various policies, trying to find the lowest penalty given my chosen weights. The optimal schedule varies a little by location in the continental US, but only by a couple of weeks.
Basically, the optimal approach is to split the pre and post sunrise time across the DST shift. As a consequence, the shift only wipes out a half hour of your sleep rather than a whole hour. This should reduce the pain associated with time changes.
Notice that the Status Quo policy adds about a month on each side. That’s a lot of extra pain, and the reason why people want a different policy.
Permanent DST (586 stupidity points)
We like DST. It makes summers nice. Let’s have DST all year round!
This is the dumbest possible policy, nearly twice as dumb as 1986 DST schedule. The US experimented with this policy in 1974, but gave up on it. The most flabbergasting thing is that anyone takes it seriously.
To be fair, this policy is optimal if you ignore the cost of getting up before sunrise. Since those costs are real and can’t be legislated away, this policy is maximally self-punishing. If we ever enact it, people will beg to take back their wish.
Permanent Standard Time (404 stupidity points)
Stop renaming time. Businesses, particularly retail, can set their own seasonal hours (as many already do). A lot of business is now electronic and independent of time-of-day. And not switching clocks would reduce a lot of complexity in computer time-keeping.
Unlike permanent DST, this policy acknowledges that there is a real sun out there, and chooses to name time like we did before DST was an evil gleam in Ben Franklin’s eye.
Smash the alarm clock (0 stupidity points)
Get up at sunrise, every day of the year, like our pre-industrial ancestors. Get to work when you are ready. In this utopia, there could still be scheduled meetings, but they are set far enough after sunrise that everyone can comfortably make it. Don’t worry, be happy.
This idea is not as insane as it might sound. With the new gig economy, working from home, etc., a lot of us can schedule our lives this way. What remains is to extend this benefit to low-wage laborers.
Method
Let’s say that the most natural time to get up is at astronomical sunrise, that moment when the first direct rays of sunlight reach you. There is a period before that called “dawn” where the sky starts to lighten. I believe that gradual increase in brightness is part of the natural wake up process, so that when the sun breaks over the horizon you are ready to start doing stuff.
It usually takes people some time to get ready for the day then travel to school or work, let’s say 1.5 hours. This means the ideal time to arrive at your desk (school or work) is about 90 minutes after sunrise. Unfortunately, in the modern world we live by the clock rather than rising naturally. The average start time of a day job in the US is close to 8:00. If you’re a student, it’s 7:30. So the typical get up time is between 6:00 and 6:30.
Sunrise varies with season and latitude. The name of that time varies with location within a particular timezone. You can calculate sunrise using this tool from NOAA. They also provide a spreadsheet for calculating sunrise times for an entire year. I took that spreadsheet and added a tab to calculate the stupidity score. You can download and try it for yourself. You can adjust the DST policy as you see fit, and change the penalty for hours before/after sunrise. Give it a try!
I chose Washington, DC as the reference location for this writeup. It seemed like a good place to measure the stupidity of policies. Ideally, a tool for actual decision-making about DST should compute the population-weighted average of a large number of locations across the country.
As you might guess, the optimal policy depends a lot on the penalty values you choose. It turns out that if you don’t care about the cost of getting up before dawn, Permanent DST is the best policy, but only by a tiny margin. If you don’t care about the cost of sleeping in, Permanent Standard Time is the best. If these penalties are equal and nonzero, the “Optimal DST” policy is still best.