Sleep disorders: Is the mobile phone to blame?

The increasing media consumption of children and adolescents has an impact on sleep behaviour. The reason is blue light. It tricks the body into thinking it is daytime.

A 2014 survey by the US National Sleep Foundation found that children sleep worse if they have mobile phones, computers or televisions in their rooms. Almost three quarters of the children surveyed between the ages of six and seventeen owned at least one electronic device, ranging from televisions, computers and games consoles to tablets and smartphones. The study found that these schoolchildren slept worse overall than those who did not have a gadget in their rooms. Sleep disturbances occurred almost daily.
Another study by Stony Brook University, NY, led by Dr Jill Creighton, found that children and adolescents who owned a smartphone slept up to an hour less than their peers. Teenagers in particular check the time on their iPhone and other smartphones when they wake up at night. However, the light from the display interrupts the sleep cycle and it is much harder to fall asleep. This is due to the blue LED light of the display. This artificial light is a short-wave light with an increased blue component in the light spectrum, as found in lighting with LEDs or light-emitting diodes. The spectral colour blue in turn lowers the melatonin level and keeps the brain awake - an effect that is probably undesirable in the evening, especially for schoolchildren.

Into bed with a blue light shower

«If you're still checking your emails or text messages at midnight, you're messing up your internal clock,» says Christian Cajochen, Head of the Centre for Chronobiology at the Psychiatric University Clinics in Basel. It has recently been shown that people have special sensory cells in their eyes that react to blue light and tell the brain whether it should keep the body awake or ready for sleep. So far, however, there has been little valid data to investigate whether the light from LED monitors is actually sufficient to disrupt the day-wake rhythm and delay sleep.
In another experiment, the researchers chose a different approach. They directly tested the effects on sleep in adolescents. According to the survey results, they spend almost four and a half hours a day in front of the TV, computer or smartphone. 95 per cent regularly check their social media pages or chats before going to bed.
«Many go to bed with a real blue light shower,» says Cajochen. The researchers then gave teenagers glasses with or without blue light filters and analysed their sleep on Friday evenings after a week at school. After a week, the researchers found significantly higher melatonin levels in the participants with glasses with filters than in the test subjects with glasses without filters. «The longer you are exposed to light in the evening, including computer screens, the longer your internal clock thinks it's daytime,» says Cajochen.
The sleep researchers therefore advise anyone who tends to have sleep problems to avoid the glow of such devices after sunset and before going to bed.

Go Offline - and five more tips for parents from Jill Creighton

  1. Entwickeln Sie eine Zu-Bett-Geh-Routine, egal wie alt ihr Kind ist. Das kann ein Bad sein, ein Buch lesen oder ruhige (!) Musik hören.
  2. Go offline! Die Stunde vor dem Schlafengehen ist elektronikfreie Zone. Die Kinder sollten an einem definierten Ort in der Wohnung – beispielsweise in der Küche oder im Wohnzimmer – ihre Gadgets einstecken und über Nacht dort lassen.
  3. Das Bett ist handyfreie Zone. Ein normaler Wecker tut es auch.
  4. Falls das Kind sein Smartphone nicht ausschaltet, sollte man die Screening-Zeit runterhandeln. 30 Minuten pro Woche weniger online sind ein guter Anfang. Idealerweise limitieren Eltern die Online-Zeit auf 60 Minuten pro Tag. So viele Minuten, wie das Kind am Handy hängt, sollte es sich auch bewegen.
  5. Das pubertierende Kind vom Sofa oder aus dem Zimmer zu kriegen, kann zur elterlichen Herausforderung werden. Sport oder Bewegung wird gerne als langweilige Pflichtübung empfunden. Creighton rät zur Kreativität. Ein 20-minütiger Spaziergang, 30 Minuten Basketball, aber auch Ämtli und Hausarbeit wie Staubsaugen, Schneeschaufeln oder Rasenmähen zählen zu entsprechender Aktivität, die je nachdem monetär entschädigt werden.
  6. Gute Gewohnheiten etablieren. Am Esstisch vom Smartphone oder Fernsehen abgelenkt zu sein, führt zu eigenartigen Tischmanieren. Die Eltern müssen hier mit gutem Beispiel vorangehen.
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More about sleep:

  • Sleep! Little child! Sleep!
  • All in one bed?
  • The four biggest myths about sleep
  • Can children sleep too little? 6 questions for the sleep researcher