My first lecture in Clinical Neuroscience was at the prestigious Charité and I can honestly say I found the experience both exciting and daunting. One of the topics that had me on the edge of my seat was how Smartphones are affecting our sleep cycles. Of course one of the smart arses in our class immediately lept out of his chair saying, “Can you now confirm that Smartphones cause sleep disruptions?”, to which our Prof (in his calm demeanour) replied, “They’re actually doing the opposite”.
When you’re falling asleep your body and mind go through a sleep cycle; first your muscles relax (Stage 1), your breathing and heart beat slow (Stage 2), you fall into deep sleep (Stage 3), which gets deeper (Stage 4), your breathing and heart beat slow even more (Stage 2 is repeated), and then finally you start to dream (Stage 5). Once you’ve finished dreaming your body usually goes back to Stage 2 and the cycle starts again from there. The entire sleep cycle can be repeated four to five times in one night.
You can tell when someone is dreaming because you can see their eyes rapidly moving around. This dreaming stage of sleep was thus termed REM sleep (i.e. Rapid Eye Movement sleep). REM sleep takes up about a quarter of your whole sleep time. This sounds a lot, but it’s also a necessity. While you’re in REM sleep your brain is busy replenishing the neurotransmitters that organise your neural networks. These neural network are essential for things like remembering, learning, problem solving and so on. In short, your brain is processing and sorting out what you did that day.
Back to my exciting first day at the Charité, our Prof explained that they wanted to measure what happened to their participants sleep cycle when they were exposed to the signals given off by mobile phones and Smartphones. At that point they’d only tested a few participants, but what they found was not sleep disruptions, they found that their participant’s REM sleep was increased. In other words, their participants spent more time in REM sleep when they were exposed to this phone signal.
Fast-forward to three years later I came across the exact same experiment all completed, written up and published (Danker-Hopfe et al., 2016). It turns out that 90% of the participants were affected by this phone signal. One third of the participant’s REM sleep increased, however the REM sleep in the others deteriorated. But this doesn’t mean that their results are “inconclusive” because the researches tested for individual differences, i.e. they looked at the differences in the results for each participant. What these results ultimately mean is that sleeping next to a phone affects each of us differently. It could affect how well rested (or unrested) we feel the next morning to how much we dream. It also means that the team at the Charité can continue looking into what the signal is actually doing to our brain cells, and if being exposed to this signal can help or hinder participants with sleep problems such as insomnia or narcolepsy.
So do mobile phones and Smartphones cause sleep disruptions?
Well that depends on the person. For some, having your phone next to you could help you sleep better and feel brighter in the morning. For others, probably best to dig out that battery powered alarm clock.
Written by Alison Holland
Danker-Hopfe, H., Dorn, H., Bolz, T., Peter, A., Hansen, M. L., Eggert, T., & Sauter, C. (2016). Effects of mobile phone exposure (GSM 900 and WCDMA/UMTS) on polysomnography based sleep quality: An intra-and inter-individual perspective. Environmental research, 145, 50-60.
Greer, M. (2004). Strengthen Your Brain by Resting It. APA: Monitor on Psychology, 35(7).