Daylight savings: There’s no spring to my step

By Karyn O'Keeffe 28/09/2012


Most of us don’t look forward to the switch to daylight savings time that will be required on Saturday night. I know I’m not. It’s not just the hour of sleep lost; daylight savings also requires a resetting of our circadian body clock. And this is where things get complicated, because the interaction of the two has follow-on effects in the days following daylight savings.

Daylight savings time is all about shifting our daylight hours so they align optimally with our working day. The upcoming transition to daylight savings time provides a way of shifting our daylight hours to be one hour later. This transition means that we shift our day/night cycle one hour forward in relation to our internal circadian body clock and therefore, to adjust to the new day/night cycle, we need to shunt our circadian clock one hour back. On Saturday night, we are going to lose an hour out of circadian clock’s day. It’s not going to like it.

Studies have shown that on average, we will get about an hour’s less sleep on Saturday night (that is, we don’t tend to strategically make up for missed sleep on that night). Missing out on sleep will help us get to bed an hour earlier on Sunday night and in fact, our bed times seem to adjust quite quickly after the switch to daylight savings time. Consistent sleep loss certainly helps push bed times earlier.

Unfortunately, our circadian body clocks don’t make such a quick adjustment. Because our circadian clocks influence our sleep/wake timing, our sleep structure changes and we often wake earlier than we’d like in the days following the switch to daylight savings time. You may recall me saying in a previous post that our circadian clock prefers to drift later. This means that it is much easier for us shift to our sleep times later, than earlier. There is some variability between individuals but in general, it takes about a week for our wake times to adjust to the new schedule. There is also some evidence to suggest that the shorter the sleep we usually get, the harder it is for us to adjust.

While it is clear that there are direct effects on sleep and circadian rhythms resulting from the transition to daylight savings time, there is conflicting evidence about the follow-on effects on waking function. Additionally, studies are not always comparable, with varying classification of degrees and type of accident or injury; and different study populations. That said, the transition to daylight savings time may be associated with increased motor vehicle and workplace accidents, as well as decreased productivity.

So what can you do to minimise the impact of the transition to daylight savings time on your sleep and waking function?

  1. Try to optimise the amount and quality of your sleep in the days leading into daylight savings. Missing out on sleep means you will cope less well. Follow good sleep habits – get a healthy amount of sleep (7-9 hours) at a healthy time of the day; avoid caffeine, nicotine and excessive alcohol; and optimise your bedroom environment.
  2. Try to shift your bed and rise times 15-30 minutes earlier in the days prior to daylight savings.
  3. Expose yourself to sunlight in the mornings leading into daylight savings. Open the curtains in the room you are in. Even better, go for a 20-30 minute walk first thing in the morning (but ensure you don’t cut into your sleep time to do this).