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Changing the clocks: night-owls, older people and adolescents are likely to suffer from "jetlag"

(Vienna, 22 March 2016) In the early hours of Easter Sunday (27 March) the clocks will go forward from 2:00 hours CET to 3:00 hours CEST, when official summertime begins. This is tantamount to a losing an hour and can lead to a mild form of jetlag for those of us whose biological clocks mark us out as night-owls, for older people and also children and adolescents and this jetlag can last for between 6 and 8 days. This point was made by Gerhard Klösch, sleep researcher at the University Department of Neurology at MedUni Vienna. The only mitigating factor: this year the Sunday in question is followed by a bank holiday, so that people are able to catch up on their sleep on Easter Monday.

"Due to their individual body clocks, between 15 and 20% of people are essentially "night-owls" because they do not feel tired and only go to sleep around midnight or even later. And this number is rising," says Klösch. "These people will really feel the loss of this hour’s sleep." The effect will be even worse if they are already sleep-deprived before the night of the changeover to summertime, that is to say if they have been sleeping on average less than the requisite 7 – 8 hours. If this is the case, they can suffer from real jetlag, with all the usual symptoms, for between 6 and 8 days. Klösch: "It is therefore important to build up your sleep quota beforehand, preferably on a long-term basis." It is much easier to cope with a short-term deficit, if your sleep is well in credit. A quick extra sleep beforehand doesn’t really work.”

The consequences are similar for older people, who might have problems sleeping anyway, and for children and adolescents, who often use the weekends to catch up on the sleep they have missed during the week. "Older people in particular complain that they feel completely disorientated for a few days after the clocks have changed. In view of increasing life expectancy and the ageing population, we seriously need to review this," explains the MedUni Vienna sleep expert.

Changing the clocks not necessary from a chronobiological perspective
Changing the clocks – whether from wintertime to summertime or vice versa – makes no sense at all from a chronobiological point of view. Chronobiology relates to the chronolgical organisation of physiological processes and repetitive behavioural patterns. Rhythms play an important part in this organisation. However, the human organism adapts itself automatically to the natural rhythm of daylight, in particular. Klösch: "We adapt in February when it starts to get light earlier. We do not need the clocks to change to do this. Daylight is an excellent timer. From the point of view of sleep research, it would therefore be much better to stick to one time system, ideally summertime, says the MedUni Vienna researcher.

Patients suffering from cardiovascular problems also feel the effects of the clock change. According to Klösch, several international studies have shown that the time change in Spring and Autumn increases the risk of heart attacks, interestingly not directly after the changeover but one or two days later. This is because the lost hour disrupts the hormone balance and other circadian rhythms. It is the stress hormone cortisol, which is released in preparation for waking up, that is largely responsible for this effect. However, cortisol release does not follow the official time but rather the time the sun rises and the body’s own internal clock. Our bodies are therefore naturally prepared to coincide with the same position of the sun, even if this means that it wakes up one hour earlier.

Other potential negative consequences of changing the clocks: "Following the changeover to summertime, there is a marked increase in the number of road accidents due to deer crossing roads at daybreak, because a lot of drivers are on the road one hour earlier," explains Klösch. On top of that, during the first few days after the changeover, a lot of people are still half asleep on their way to work and this also increases the risk of accidents.

Five research clusters at MedUni Vienna
In total, five research clusters have been established at MedUni Vienna. In these clusters, MedUni Vienna is increasingly focusing on fundamental and clinical research. The research clusters include medical imaging, cancer research/oncology, cardiovascular medicine, medical neurosciences and immunology. Research into sleep falls within the remit of the medical neurosciences cluster.