Daylight saving: a dark side?

We are in the throes of Daylight Saving (DS). In October each year, we wind our clocks forward one hour and our body clocks strive to adapt to the time shift. Daylight saving is a modern phenomenon. In 1909, a JAMA editorial entitled “To increase daylight saving time” observed that “it will certainly be an improvement if we can take more of our sleep in darkness and more of our waking hours in daylight”. More than a century earlier, Benjamin Franklin had suggested DS, but it was not until World War I that catastrophic circumstances precipitated its adoption by several European countries and the United States.

Closer to home, the observance of DS across three time zones can be chaotic, especially when Western Australia, the Northern Territory and Queensland have opted out. This confusion is further compounded by the fact that the states adopting Eastern Summer Time cannot even synchronise a commencement date. But this may well be a trifle when one considers the possibility that DS may have a “dark side” — indeed, it may even be a risk to your health!

If you Google “disease and daylight saving”, you are confronted with more than half a million citations on ill health and DS, including major adverse events such as heart attacks and strokes, as well as the usual occupational injuries.

While it may be true that there is a clearly established link between occupational accidents and disturbance to the circadian rhythm, the association with metabolic diseases is more speculative and relatively soft.

Given Australia’s unique geographic DS time distribution, we are a living laboratory, well placed to study the evidence for a possible link between DS and its dark side. Meanwhile, in the absence of such evidence, let us remember one of Benjamin Franklin’s favourite maxims: “Early to bed and early to rise makes a man healthy, wealthy and wise”.