A ReLACSing Blog #19: For Daylight Saving Time, at Least It’s Easier to Fall Back

On Sunday, I will wake up at 5:30 am (or so the clock says) to the excited banter of children starting the weekend day way too early. Not to keep, ahem, shining light on this important issue, but as we approach the bizarre biannual practice of doing the whole Daylight Saving Time clock change, I figured it would be a good time to talk about why falling back is easier than springing forward. 

As I addressed in the first-ever ReLACSing blog post, the switch back and forth from Daylight Saving Time (DST) is terrible for sleep, health, and many other aspects of societal function and should be done away with. At the time of this blog post, the United States Senate has passed the Sunshine Protection Act (not to be confused with the Physician Payments Sunshine Act, which is an important law that requires disclosure of financial relationships among doctors and hospitals with device and drug companies). The Sunshine Protection Act would make DST permanent and eliminate the clock changes. However, for an equal decibel level of sleep specialists shouting, “YES!” when the time change elimination was announced, there was shortly thereafter a cry of “Noooooooo!” when we found out about permanent DST. They made the right decision to settle on one time, but they went in the wrong direction. Most sleep physicians and sleep & circadian rhythm researchers would argue that good ol’ Standard Time should be adopted in the US. This is also the message from the American Academy of Sleep Medicine, the nation’s largest professional organization of sleep physicians and researchers. This initiative, however, has stalled in the House of Representatives, so it’s anyone’s guess whether permanent DST will, ahem, see the light of day. 

I won’t belabor the analysis of this as it was addressed in Blog #1. I will say that my 11 year-old this week did suggest that we compromise by adopting 30 minutes of DST year-round. This would be interesting as well, but imagine the confusion if we were 30 minutes off from the rest of the planet! In a national committee of sleep physicians, it’s hard enough to figure out during our teleconferences that the docs in Boston and New Jersey are in the same zone as me in Michigan but an hour off from the other midwesterners in Nashville and Chicago. Try figuring out when to meet with a colleague in Paris if we were off by an additional half hour.

Regardless of the state of DST, falling back is easier than springing forward. There are several reasons for this. It’s not just that you get to sleep in an extra hour on Sunday. In fact, I mentioned I would be up at 5:30 am because the kids, with their very healthy circadian rhythms, will simply get up at the same time of their biological clock regardless of what their dresser clock states or when its backlight turns yellow to indicate it is time to get out of bed and disturb their parents. They’ve been getting up every day at 6:30 am and now it will be 5:30 am and that may persist for days or weeks. 

The first main reason that it is easier to fall back is that we have evolved the ability to keep ourselves awake when physically able to sleep. Conversely, we do not have the ability to force ourselves to sleep when physically unable to sleep (depending mostly on the combination of the biological clock and homeostatic sleep drive/fuel to sleep). In the fall, when the clock moves back, it is much easier to keep ourselves awake for that extra hour than it is to go to bed an hour earlier in the spring. If your bedtime is normally 11 pm and with the time change, 11 pm is now midnight this weekend, most of you can push through and stay up until the new 11 pm instead of dozing off at your normal time of what is now 10 pm. In the morning, it’s not a big deal to wake up an hour earlier, or allow yourself to sleep in and wake up at 7 am (which is really 8 am to your body). Eventually by allowing yourself to sleep in to the desired clock time over the upcoming post-“fall back week,” your circadian rhythm will acclimate to the new times by moving forward or delaying.

The same is true for jet lag or time zone travel. Most find it easier to travel west a time zone or two than the opposite direction. Moving to a western time zone is identical to falling back with DST. You normally wake up at 7 am in Cincinnati and then fly to Houston, and 7 am is now 6 am to your body in the central time zone. Going east or springing forward is much more of an issue. If you normally go to bed at 11 pm and the time springs forward, then you are forcing yourself to sleep at 10 pm to your body. Unless sleep deprived, you probably will not fall asleep until midnight, which would be 11 pm to your body. You also have to wake up an hour earlier when you spring forward. This difficulty of falling asleep earlier will only resolve after you have woken up earlier for several days. As I have said previously in this blog and in video, the time you wake up sets your bedtime, not vice versa as you may have been taught. However, some individuals are so sensitive that they have trouble adapting to even the one hour change in the spring, taking much longer than a few days to acclimate. Some individuals actually remain off-cycle all the way until the next time change in the fall!

A second major reason is that the length of the biological clock is not actually 24 hours, it’s a little longer than 24 hours or about 24.2 hours. The length of an individual’s circadian rhythm is called the tau. I know that COVID variants have tarnished most Greek letters at this point, but I think tau is still OK to use among polite company. If a full day is 24 hours, then how do we synchronize with the Earth’s rotation? Our biological clocks are affected by certain environmental cues, called zeitgebers (from German, not Greek), most prominently light and darkness, but daytime activity, meal timing, sounds, and many others to a lesser extent. This helps the body adjust back to 24 hours in synchrony with the Earth’s rotation. There are certain variations of the biological clock that contribute to alternate time preferences including advanced sleep-wake phase and delayed sleep-wake phase. Many with an advanced sleep-wake phase have a tau of less than 24 hours. If they had no daytime cues, then they may fall asleep and wake up slightly earlier every day. The advanced sleep-wake phase people including your manager who schedules team meetings at 7 am in the conference room (do people still meet in conference rooms?) or like every surgeon who thinks patients should be examined at 5 am before surgeries scheduled starting at 6:00 am in the OR. Those with a delayed sleep-wake phase often have an extended tau, possibly longer than 25 hours in duration. These individuals would progressively go to bed later and wake up later every day if not exposed to zeitgebers. These include your musicians, artists, performers, or computer programmers, i.e. those who may not be at the mercy of those advanced sleep-wake phase bosses who make them meet at the conference rooms that may not exist at 7 am. In most cases, the tau of longer than 24 hours helps to shift the body’s rhythm later, eventually in line with the later timing of all activities relative to sunrise and sunset during the fall time change. 

With the exception of those with advanced sleep-wake phase, most will not have as much trouble adjusting to the fall time change. Those with young children, however, can be observant of the children’s wake up times, and I guarantee that most of them will take a while to shift later in the morning due to the strength of the circadian rhythm. For those that struggle with the fall time change, gradual movement toward the one hour change is the best, perhaps 10 minutes each day leading up to the Sunday change, by staying up 10 extra minutes each night. Perhaps a little more intense light exposure at night close to bedtime and blue-blocking glasses for the first two hours after waking up may help for a few days as well. Again, this will not be necessary for most of you.

Though I wish I could say this is the last time we will be falling back for Daylight Saving Time, at least this week is not so bad. Enjoy getting back some sunlight to your morning and go outside to watch the sunrise this week!

-Andy Berkowski MD of ReLACS Health, displeased to be woken up at 5:30 am on Sunday (but at least it’s really 6:30!); conference rooms are banned at ReLACS Health by the way, and there are never 7 am meetings for ReLACS Health staff