In March 2019, the German Teachers‘ Association approved of the decision of the EU Parliament to abolish the time change. However, Heinz-Peter Meidinger, president of the association, thinks there is a health risk for students if a country switches to summer time permanently: The probability of sleeping and learning problems, depression and diabetes has demonstrably massively increased, he is quoted by the news portal “Merkur.de”. The empirical basis for this claim is good but not perfect.
Basically, humans adjust their internal clock to the time when the daily sun position has reached its highest point, the biological noon. For example, the biologist and medical scientific journalist Maren Schenk describes the relationships between the organism and time change in the “Deutsche Medizinische Wochenschrift”, a German medical journal of the Thieme Verlag in Stuttgart, published on 25 October 2012. If the clock is put forward by one hour this system falls into imbalance, which is the reason why many people suffer from the time change and complain about sleeping disorders and organic ailments.
On 29th of March in 2018, the online magazine “Riffreporter” published the article: “Die Zeitumstellung ist kein Mini-Jetlag, sondern schlimmer” (“The time change is not a mini jet lag, but worse”). Chronobiologist Till Roenneberg of the Ludwig-Maximilians-University in Munich thinks that the clock change is not the only health risk, but there’s also the already existing lack of sleep in the population. “The current summer time regime simply moves our social obligations eastward for one time zone without leaving our biological time zone,” says Roenneberg. Above all, pupils and students are affected by the permanent summer time, because at a young age people’s inner rhythm shifts. With too little sleep it is increasingly difficult to process the material taught. According to the above statements, a biological adaptation to the changed time for humans is therefore not really possible. The clock change without a changing course of the sun alongside the chronobiological rhythm adapting to that change can subsequently lead to permanent drowsiness and fatigue.
Poor sleep leads to health problems
The sleep hormone melatonin plays a major role in the discussion of the permanent changeover to summer time. The hormone enormously affects the biological clock of the human body. It is secreted during the dark hours by the pineal gland of the brain. In the morning, the melatonin level drops again. If the biological rhythm is ignored or manipulated as in time change or during periods of shift work, this can lead to significant health consequences. The journal “Life Sciences” published a study called “Association between light at night, melatonin secretion, sleep deprivation, and the internal clock: Health impacts and mechanisms of circadian disruption” on March 15th, 2017. It shows that especially in shiftworking, the effect of artificial light and thus the suppression of natural melatonin secretion at night leads to a disruption of both the circadian system, the sleep-wake rhythm of humans and to chronic sleep deprivation. Numerous epidemiological studies have shown that this desynchronization of night shift workers has long-term unhealthy consequences such as cancer, diabetes, cardiovascular risk and obesity.
As a result of the changeover to summer time, the adaptation process of the organism to the light conditions is thus considerably disturbed and also has an effect on other biological processes in the human body. On the 16th of March, 2011 the German medical journal “Der Internist” published a scientific article titled “Schlechter Schlaf als Risikofaktor für das metabolische Syndrom” (“Poor sleep as a risk factor for the metabolic syndrome”). According to epidemiological studies, there is clear evidence of a link between sleep duration, sleep quality and the risk of developing diabetes mellitus as part of metabolic syndrome, the combination of insulin resistance leading to type 2 diabetes, abdominal obesity, hypertension and lipid metabolism disorder. According to the journal, several studies show that the risk of developing type 2 diabetes mellitus with a sleep duration of less than 5 hours or more than 9 hours is twice as high as with an 8-hour sleep duration, including “The Nurses Health Study” from the 1980s.
Expert asks for a cautious interpretation
But not only the duration of sleep but also the qualitity of sleep has an influence on the development of diabetes. Clinical experimental studies such as “Slow-wave sleep and the risk of type 2 diabetes in humans” in 2008 showed that poor sleep is one cause of a disturbed energy metabolism. This leads to increased appetite and hunger, a reduction in insulin sensitivity, i. e. the sensitivity of the body cells to insulin, a heightened appetite and hunger sensation as well as a lack of exercise in everyday life. All these are factors and triggers for the metabolic syndrome in humans. Diabetes and the metabolic syndrome can certainly be triggered by other sleep disorders. Endocrinologist PD Dr. med. Norbert Lotz of the Diabetes Center in Kempten, Bavaria, however is of the opinion: “A frequent coincidence of diabetes mellitus or the metabolic syndrome and sleep disorder is proven only for the sleep apnea syndrome.” Therefore sleep apnea, accumulated nocturnal breathing pauses with oxygen deficiency in the brain, must be excluded in advance in order to evaluate the described relationships. This disease has been proven to increase the risk of diabetes. That’s why the conclusion that sleep deprivation generally leads to an increased risk for this metabolic disorder is not sufficiently proven by randomized studies. Here still exists considerable need for medical research.
Summing everything up, it is difficult to regard the statement of the German Teachers’ Association that a permanent switch to Daylight Saving Time leads to sleep or learning problems as well as to depression and diabetes as a given fact. The switch certainly carries risks for learning and sleep problems. But so far current medical studies show no clear evidence for the development of type 2 diabetes, metabolic syndrome and defined mental illness due to general sleep deprivation. Therefore the claim is judged to be only mostly true.
RESEARCH | ARTICLE © Annika Bingger, Hochschule der Medien Stuttgart, DE
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