Switch it off: why your phone is harming your sleep
A digital device in the bedroom, even if it isn’t used, is associated with poor sleep
In one Harvard study participants who read on light-emitting devices took longer to fall asleep, experienced less REM or dream sleep, and had higher alertness before bedtime than people who read regular books
“I’ve tried acupuncture, reflexology and reiki. I’ve taken herbal teas. I’ve put lavender in the bath. I’ve tried melatonin. I’m on magnesium at the moment. I’ve done mindfulness. I take anti-histamines anyway for years. I’ve been to a nutritionist. I’ve tried a flotation tank.”
Like one in three of us, 31-year-old radio producerLaura Donnelly is not getting enough sleep. “I’m beyond tired. I don’t even feel it anymore. But I can’t remember the last time I felt fully refreshed.”
Worldwide, at any given time, 10-30 per cent of the population is having trouble sleeping. For an unlucky six per cent like Donnelly, these problems persist for more than a month.
On an average night, Donnelly gets four or five hours’ sleep. On a bad night, of which she gets a few a year, she gets no sleep at all. “I’m probably my own worst enemy because at 1am, I get performance anxiety about the fact that I only have five hours left. Any time I read a study that says people who sleep poorly are likely to develop x, y, or z later in life, I think ‘that’s me’.”
Recent evidence suggests she is right to be concerned. A report by the World Health Organisation warns that sleep deprivation is as much a risk factor for heart disease as smoking, lack of exercise or a poor diet, leading to claims that it is the “new smoking” – although this idea seems to have gained currency when Arianna Huffington released a book on the subject in 2016.
A 2014 study published in the Journal of Neuroscience showed the brain cells of mice died off when they were deprived of sleep. Other research from France showed the brains of workers who had been on night shifts for a decade had aged by an extra 6.5 years.
“We know that poor sleep is linked to cancer, weight gain, diabetes, immune system problems, skin damage and increased cardiovascular disease,” says Breege Leddy, a sleep physiologist who runs the Insomnia Clinic in Co Cavan. “Those are the long-term problems. We also have to think about the short-term consequences like road traffic accidents or the risk of depression or the impact on decision making.”
We have a clearer picture than ever of how important sleep is to our overall health. And yet, we’re getting less of it than ever. A study of 20,000 people in the UK found that the number of those diagnosed with insomnia, and the number of those using sleep medication, each doubled between 1993 and 2012. ‘Worry’ was the most common cause of sleep problems. But there could be another culprit – one that’s never more than arm’s length away during the day, that sleeps beside you while you sleep.
James Casserley, a 42-year-old librarian, has suffered from sleep problems since childhood. “Once I go to bed, I’m wide awake. I’ve tried going for walks in the evening, taking warm baths, doing early evening exercise. I’ve stopped eating after certain times, I cut coffee down hugely and I’ve never smoked and hardly drink. But nothing has made any difference.”
However, he admits, there’s one habit he has found hard to break. “I would be guilty of resorting to whiling away the sleepless hours using the phone. When you’re lying there and your body feels like it’s crying out for sleep, but your brain is running too fast, and you’re too tired to pick up an ordinary book, you sort of give into temptation.”
Donnelly avoids her phone at night, though she too sometimes “gives in to temptation”. It is a phenomenon familiar to many. In the Ikea study, 54 per cent of people said they checked social media before bed, and almost 23 per cent said they play computer games.
Researchers have known for a while that the blue light from your digital device messes with your circadian rhythms. What they haven’t appreciated – until recently – is how dramatic the impact can be.
Melatonin is the chemical that signals to your body it is time to sleep. It is present in the body at low levels during the day, and begins being released a few hours before bedtime, peaking in the middle of the night. As little as eight lux – dimmer than most table lamps – has an effect on melatonin levels. Blue light, of the kind emitted by digital devices and energy-saving bulbs, activates photoreceptors in the brain which boost alertness and suppress melatonin, altering circadian rhythms.
In a study published in July by researchers at the University of Houston College of Optometry, participants who wore glasses to block short wavelength – or blue – light and continued using their devices as normal until bedtime, experienced a 58 per cent increase in their night-time melatonin levels and slept for 24 minutes longer on average than participants who did not use the glasses.
Put differently: turning off your phone three hours before bed is a more effective way to boost your melatonin than taking a melatonin supplement.
In another Harvard study, participants who read on light-emitting devices took longer to fall asleep, experienced less REM or dream sleep, and had higher alertness before bedtime than people who read regular books. The effect lasted all night: after eight hours of sleep, those who read on digital devices still felt sleepier and took longer to wake up.
A 2016 study at King’s College in London found that children using devices at bedtime had more than double the risk of a disrupted night’s sleep. The study found that the very presence of a media device in the bedroom, even if it was not in use, was associated with an increased likelihood of poor sleep.
“Last year I did a talk for a group of transition year students on sleep – I asked for hands up to see who had a smart device in the bedroom. Every single hand went up,” says Leddy.
“Smart devices are part of our life, but when it comes to sleep we have to use them with caution. The effect they have on sleep can really impact our functioning in two ways. The blue light reduces our production of melatonin, but the cognitive stimulation is another issue. If you wake up in the night and reach for your phone to check the time, and then decide to read your notifications, the whole cognitive stimulation process kicks off.”
“It is something I’d be very aware of,” says solicitor Gwen Bowen, a mother of three who occasionally suffers from disrupted sleep. “I do use my phone at night, even though I know it’s against the best advice.”
Where her kids are concerned, Bowen is stricter. “If they have a device in the room, they are going to use it. If there is some crisis or an issue, they can end up having their sleep disturbed because there are messages going back and forth all night. I’ve picked up my children’s phones during the night and seen message notifications coming in at 1.30am and 2am. So I don’t allow devices in the bedroom.”
It’s not just teenagers who are glued to their digital devices until late at night, says fifth-class teacher, Ciara Brennan. “Even young children stay up until the early hours watching stuff that might not be suitable for their age group. This is concerning for many reasons, not least from an internet safety point of view, but it does also have a major impact on the amount of sleep they get.
“You can see it in a child’s attention span the following morning – whether they’re able to follow a task and stay with the lesson. It’s very easy to pick out the kids who haven’t had enough sleep the night before.”
So what should people do to protect their own – and their children’s – sleep habits?
Most experts, including Leddy, recommend simply switching off two to three hours before bed and not allowing any devices in the bedroom. But if you – or your child – really can’t face that, check if your phone has a blue light filter or “night mode”, or use anti-reflective screen covers on your devices, or just wear a pair of amber-tinted sunglasses. However, as Leddy points out, these lenses don’t counteract the effects of cognitive stimulation.
The broadcaster Rick O’Shea suffers from occasional bouts of insomnia which, he says, he has brought under control by enforcing a strict no-tech-after-9pm rule.
“I don’t do social media after 6pm, and I don’t even watch TV after 9pm, and I do think it made a difference to my sleeping. I think our relationship with sleep is radically different now than it was 20 years ago. We’re not getting enough of it, and we’re not taking seriously enough the notion that this thing you carry around with you constantly – your phone – can screw up your circadian rhythms.”