Scientists Might Have Figured Out How to Use a Phone in Bed Without Your Affecting Sleep

12 AUGUST 2016

We all know that using phones and tablets in bed can mess with our bodies in a whole bunch of ways, but researchers have found a possible solution: expose yourself to more light during the day.


The team found that young adults who got a lot of daytime bright light exposure were less likely to experience disrupted sleep patterns after using their gadgets at night. 

"Our main finding was that following daytime bright light exposure, evening use of a self-luminous tablet for 2 hours did not affect sleep in young healthy students," said neuroscientist Frida Rångtell from Uppsala University in Sweden.

For the study, 14 participants were exposed to bright light – approximately 569 lux, which is slightly less bright than an overcast day – over a period of 6.5 hours. Afterwards, half of the participants were asked to read a book on a tablet before sleeping, while the others were given a physical paperback.

A week later, the volunteers carried on reading, but swapped over from tablet to paperback, or vice versa. Each time, sleepiness, sleep quality, and melatonin levels were measured.

The team found that the bright light exposure appeared to counter any wakefulness brought on by the evening gadget use. 

There are some limitations to the study to bear in mind: it was only carried out on an extremely small sample, and the researchers note that because the participants were reading books rather than browsing the internet, their experiment doesn't take into account the "emotional arousal" associated with checking emails or Facebook – something that could still affect your sleep quality irrespective of light exposure.


That said, the findings do point to the possibility of us mitigating the damaging effects of blue light on our sleep patterns by simply making sure we get outside more.

Blue light is emitted by smartphones, tablets, and other gadgets, and effectively tells the brain to stop producing the hormone melatonin - the chemical signal that lets our bodies know when it's time for some shut-eye.

It's because of this effect that Apple recently introduced a Night Shift mode on the iPhone, which cuts down on the blue light given off.

"Our results could suggest that light exposure during the day, e.g. by means of outdoor activities or light interventions in offices, may help combat sleep disturbances associated with evening blue light stimulation," said one of the team, Christian Benedict.

Scientists are still exploring the ways in which blue light can affect our bodies and our sleep patterns. Mobile phones have only been around for 20 years or so – and newer devices like smartphones and tablets with big bright screens only in the past few years – so at this point, long-term conclusions are difficult to make.

But there's already some evidence that blue light could cause problems with attention span and memory function, as well as disrupting sleep, and considering that most of us go to bed with our smartphones in reach, we're talking about issues that could affect millions.

The researchers plan on carrying out further investigations with a greater sample of participants, but until we know more, you should probably limit your bedtime Netflix watching if you want a good night's sleep. And if you must, at least make sure you've spent some time outdoors first.

The findings have been published in Sleep Medicine.