• Question from:Shawn Halayka

Is there any research showing that the non-constant light from an electronic screen (or LED Christmas lights) has a negative effect on our circadian rhythm?

Recent research showed that electronic screen viewing had a negative effect on the emotional well-being of children. The research showed that non-electronic sedentary activities like pencil and paper homework did not have the same negative effect.

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  • University of Bristol
  • Posts: 2,462

I have spoken to 2 senior professors who are both experts in sleep and circadian rhythms and the answer is unequivocally that there is no evidence  that light from an electronic screen has a negative effect on circadian rhythms. Both however made the point that extended time on computers in the evening/night which is often associated with a reduction in sleep is in turn strongly associated with poor sleep pattern, negative scores psychologically and obesity (in children).

Now onto the paper you mention: it was just published in the journal "pediatrics".

It is an interesting and well conducted study and predictably the findings have been taken out of context and hyped by the media. It actually says that the association (note it is an association and NOT a  causal relationship) of PC use and higher scores in a negative well being psychological questionnaire is "weak". Importantly there was also an association with degree of puberty in the 11yr old children included in this study. Thus it is possible that the children later in puberty have higher scores in the negative well being psychological questionnaire and thus spend more time on their PCs. The other limitation of the study as the authors state in the paper is they could not tell which came first. In other words did the children score less well and then start using their PCs more or vice versa. To put it another way, just because A and B are associated does not mean A causes B. B could cause A or alternatively C could cause both A and B.

The reason I have gone into this in some detail is to emphasise the importance of reading and critically analysing the information we read in the press. Very often journalists quote out of context, put their own "spin" on the findings and sometimes just get things wrong. My advice is to read the original paper where possible and to think about what the data really means and the limitations of the study.

If after doing that you have questions or are unsure of the meaning then you know who to call - AAB!