In the night between Saturday 25 and Sunday 26 March, the hands will go forward by one hour, thus sanctioning the return of summer time. The two passages, in spring and autumn, are like two small jet lags and the impact on health is quite significant. For example, in the days following the movement of the hands, there is a higher than average number of heart attacks, accidents at work and road accidents. Some experts point out that summer time deviates from the circadian rhythms of the human body to a greater extent than standard timewhile for the Italian Society of Endocrinology it could increase the danger of negative effects on metabolism and the cardiovascular system. “The main problem from the point of view of health concerns precisely the transition period, in particular the spring transition between standard time and summer time seems to be more problematic”, explains Professor Joseph Plazzi, director of the Irccs Sleep Center (Institute of Neurological Sciences of Bologna). “Several studies”, continues Plazzi, “including some meta-analyses, have demonstrated a slight but significant increase in the incidence of acute cardiovascular disease (especially heart attacks) from a blow, in the days following the time change. This could depend on the effect of a partial acute sleep deprivation, while the body tries to readapt to the new cycle, with associated increase in activity of the sympathetic autonomic nervous system (with effects such as tachycardia and arterial hypertension) and increased systemic inflammatory state. Furthermore, in the same transition period, negative effects on the psyche are observed, ranging from subjective malaise, worsening of mood, up to the increase of the suicide rate”.
Trying to find a compromise between energy impact and human health, would the permanent daylight saving time solution be welcomed?
“Without going into the merits of economic and energy issues, which do not fall within my competence, permanent daylight saving time could actually be a viable solution from a health point of view. In fact, since the main problem of summer time is the time changeover periods, these would disappear with permanent summer time. The adaptation of the individual’s circadian clock to alternating light and dark is determined by multiple factors influenced by genetics and the environment. We consider that each person has a chronotype that influences his adaptation to social rhythms (those established by the hands of the clock). Everyone can be predominantly ‘owl’, i.e. preferring more activity in the evening and sleeping longer in the morning; or be ‘lark’, with better performances in the early morning and early bedtime. From this point of view, our society, regardless of solar time and summer time, may not be completely aligned with individual needs, as any type of shared time is a form of convention”.
So the other possibility of extending summer time a little would not be healthy…
“For the reasons explained, given that the negative impact of summer time depends essentially on time changes, extending the summer time period would not substantially improve the health problems of the population”.
Can anything be done on an individual level to mitigate the impacts of the time change?
“First of all, in these phases, it is essential to maintain what is defined as one ‘regular sleep hygiene’. For example, go to bed only when sleeping and get up when you wake up (therefore without forcing yourself in one or the other case), avoiding exposure to bright screens (computers, TVs, smartphones) before going to bed . Then, in case of low tolerance for the changeover to daylight saving time, try to adapt to the new rhythm as gradually as possible, even if working rhythms in this case can be an obstacle. Finally it is important do not independently resort to drugs, especially hypnotics, without medical supervision, because there is the risk of establishing vicious circles of alteration of sleep rhythms”.
