Animal studies show that smartphones and tablets can cause puberty earlier

Smartphones, tablets, computers, TVs and tungsten lamps; they all emit a high proportion of blue light. Now, a study by Turkish researchers published last July has made a worrying discovery. In one experiment, they were able to establish a link between blue light and the early onset of puberty in rats.

Precocious puberty in children usually has no clear trigger, the American Association for the Advancement of Science (AAAS) writes in an article. Factors such as obesity, stress or environmental influences are considered likely. In any case, it is becoming increasingly clear that puberty begins prematurely in girls and boys – most recently especially during the Corona crisis. According to the association, a possible reason for this period could also be the increased use of devices that emit blue light.

In the experiment, 18 male rats were divided into three groups: a control group exposed to a normal light cycle (12 hours of light, 12 hours of darkness), a 6-hour group (6 hours of light, 6 hours of blue light, 12 hours of darkness). ) and most recently a 12 hour group (12 hours blue light, 12 hours dark).

The researchers found that the longer the rats were exposed to blue light, the earlier puberty started. In addition, damage to sperm production and testicular tissue was found in these rats. A previous study by the same research group had found similar results in female rats.

However, the researchers emphasize that this is an animal experiment and no direct conclusions can be drawn about humans. Further research is needed into this.

Chronobiologist Christian Cajochen from the University of Basel is also reluctant to draw conclusions from animal experiments on humans. Human puberty is influenced by many factors, he says when asked. Diet, genes and the environment can lead to early puberty.

The influence of blue light on this is controversial in science, according to the lighting expert. The usefulness of animal testing for knowledge about humans depends greatly on the question. In the present case, a conclusion according to Cajochen is too vague. The facts are too thin for that.

However, the fact that blue light, i.e. light waves of around 480 nanometers, has an influence on humans is beyond dispute, according to the chronobiologist. For example, this light regulates our melatonin levels and therefore also our internal clock.

Daylight is a mixture of all light frequencies and therefore contains a lot of blue light. Daylight stimulates special photoreceptors in the eye, which are connected to parts of the brain that regulate our alertness level and our internal clock, says Cajochen.

Due to the increased use of artificial light and electronic devices in the evening, too much light can disrupt the internal clock, suppressing melatonin production, according to the lighting expert. According to the chronobiologist, the internal clock can become unbalanced, leading to a shift in sleep times into the morning hours and associated fatigue during the day.

However, light with a high blue content is not fundamentally harmful to humans. Cajochen always recommends healthy lighting hygiene. It is not recommended to use blue enriched light until late at night. During the day, especially in the morning, it is useful to calibrate your internal clock. In the dark season, light therapy may be recommended for people who suffer from the winter blues or feel tired in the morning. (aargauerzeitung.ch)