Many of us are used to clutching our phones in the moments before hitting the lights and trying to get some sleep at night.
But if you struggle to sleep and end up tossing and turning in the hours that follow - what you're doing on your phone at night could be the problem.
A new study has found posting to social media in the 60 minutes before trying to sleep can actually prevent dropping off by up to three hours.
Researchers found that posting within the crucial time window means users brains are more likely still tuned into their phone while trying to sleep.
This can be due to the anticipation of a response to the post, or response causing a device to signal a noise or light.
Researchers tracked more than 51,000 Reddit users as part of the study - tracking when they posted and comparing to how long they then stayed on the site.
Dr William Meyerson, of Duke University, said: “This could be the result of several factors — from screen lights disrupting the circadian rhythm, to the anticipation of a response.
"Reddit users are more likely to stay up past their bedtime and post on nights when they posted an hour before bedtime, especially if they were active on high-engagement forums."
The study, published in the Sleep Medicine journal,
researchers have raised concerns that staring at the blue light of the screen prevents the body's natural sleep cycle from kicking in, blocking the hormones that make us drowsy.
The latest study, published in Sleep Medicine, tracked Reddit users post times across 16 years - around 236million posts measuring how many were made after a user’s bedtime.
They found were more likely to remain on Reddit one to three hours after their bedtimes on nights when they posted in the last hour.
Sleep experts have long preached the benefits of avoiding blue lights from such electronic devices as a smartphone or tablet before bed.
What is blue light?
Most of us know sunlight contains visible light rays as well as invisible ultraviolet (UV) ones. But visible light comprises a range of different coloured rays, which each carry different amounts of energy.
“Blue light is one of the visible parts of the electromagnetic spectrum so it’s one of the colours we can see,” says Romesh Angunawela, from Ophthalmic Consultants of London and consultant eye surgeon at Moorfields Eye Hospital.
“It has shorter wavelengths than any other visible colour. It’s close to UV, which is even shorter, but not visible to us.”
As well as being present in daylight, blue light is emitted by fluorescent lamps and LED devices such as computers, smartphones, TVs and tablets.
“Electronic devices tend to emit more light in that spectrum than natural light does,” says Angunawela.
This, plus the time we spend on our devices and their proximity to our faces, has health professionals concerned about the potential consequences.
How does it affect sleep?
You probably feel a twinge of guilt when checking your smartphone in bed – we all know devices should be kept out of the bedroom.
“There’s clear evidence blue light exposure can affect sleep patterns and circadian rhythms,” says Angunawela, talking to Healthy magazine.
When it comes to us fully understanding the lasting effects of blue light, it is a waiting game.
“These issues are theoretical because we think long-term exposure will be problematic, but at the moment we don’t have enough long-term data,” says Angunawela.
“But the day-to-day eye fatigue and headaches – that’s already happening. It doesn’t do any harm to protect yourself, so it’s worth taking measures to do so.”
