Will you spring forward only to fall back into bed next Monday? At least it’s a bank holiday so you will avoid the usual double whammy of a Monday at work with reduced sleep.
Next Sunday at 2am sees the beginning of Daylight Saving Time (DST). Welcomed by most for the additional evening leisure time it offers, the loss of one hour’s sleep does require some short-term readjustment.
Recent research has once again highlighted health risks associated with the practice.
Turning clocks ahead an hour in the spring or turning them back again in the autumn is associated with a temporary increased incidence of stroke, a Finnish study shows. The increased stroke risk just after a transition to and from DST is probably related to interrupted sleep patterns, according to lead author Dr Jori Ruuskanen, of the University of Turku.
He and his colleagues studied the effects of transitioning to and from daylight saving time on stroke hospitalisations across Finland from 2004 to 2013.
They compared the incidence of ischaemic stroke – the type that occurs when a clot travels in to the brain and blocks the blood supply – among 3,303 patients hospitalised during the week after the introduction of DST with the stroke rate among a control group of 11,801 patients hospitalised two weeks before and two weeks after the transition week.
They found that the incidence of stroke increased during the first two days after transition. Thereafter the effect was diluted. Another positive is the finding that the DST phenomenon does not cause any additional strokes. Rather it appears the transition may makes strokes that are inevitable occur sooner.
A 2013 study of almost 1,000 patients at two Michigan hospitals compared admissions for heart attacks during the seven days after the move to daylight saving to two weeks previously. Researchers found 17 per cent more heart attacks after “springing ahead”, with the biggest spike occurring on the first day after the clock change.
Sleep deprivation
So what is going on that might explain the DST effect on cardiovascular health? There is some evidence partial sleep deprivation can increase levels of adrenaline. And the stress of having to drag your sleep-deprived self from bed to go to work at what it feels is an ungodly hour can make platelets aggregate and the blood more likely to coagulate. It’s all part of the circadian misalignment of our internal body clock.
However, researchers can only speculate on the reasons for the association between a greater stroke and heart attack risk within two days of a time change because so far studies have not addressed causal associations.
Like a lot of medical research we are left with more questions than answers.
Does the same cardiovascular risk apply when we travel to mainland Europe and “lose” an hour as we move from Irish Standard Time to Central European Time? Another interesting question is whether people in areas that don’t have daylight saving time (the province of Saskatchewan in Canada, for example) have fewer strokes and heart attacks.
Whether there is a difference on the Monday after the time change depending on whether it is a regular work day or a bank holiday may be worth looking at also.
Mondays in general see more heart attacks than any other day of the week. But back-to-work Monday after the time change brought 24 per cent more heart attacks than usual, according to a 2014 study. However, the rest of the post DST week saw fewer attacks than average – all of which suggest the switch to daylight saving makes vulnerable people have heart attacks sooner.
It seems the Boomtown Rats were right about not liking Mondays. But I’m not sure we should get into an additional knot of anxiety about the immediate post-DST period. Far better to embrace the extra light, revelling in the opportunity it offers to get out and be healthy.
mhouston@irishtimes.com @muirishouston