Terrible night's sleep? Blame your smartphone, tablet, laptop, and other devices that new research has pointed the finger at for keeping us up at night.
It isn't the constant need to check emails or chart 'likes' on our facebook posts, but the artificial light screens emit that disrupt the body's natural rhythm and cut into our sleep time.
Writing in science journal Nature, Harvard's head of sleep medicine Professor Charles Czeisler has called for research to help develop ways of counteracting the effects of artificial lighting on sleeping patterns.
In the 50 years leading up to 2000, Professor Czeisler writes, the average person in the UK increased their use of artificial light sources by four times, and sleep deficiency rose in line with this as did the consumption of caffeine to stay awake.
He also cited a study that revealed 30 per cent of working adults in the US and 44 per cent of night workers reported getting less than six hours sleep a night on average.
This decline in number of hours we are sleeping each night thanks to screen-time, Czeisler writes, affects public health, and puts us at greater risk of obesity, diabetes, heart disease, depression and stroke in adults, and concentration in children.
"There are many reasons why people get insufficient sleep in our 24/7 society, from early starts at work or school, or long commutes, to caffeine-rich food and drink," he says.
"But the precipitating factor is an often unappreciated, technological breakthrough: the electric light. Without it, few people would use caffeine to stay awake at night.
"Many people are still checking email, doing homework or watching TV at midnight, with hardly a clue that it is the middle of the solar night."
An Australian study released this week revealed that children as young as eight years old had access to an average of between three and four internet enabled devices, and one in four tweens — kids between the ages of eight and 12 — was still online after eight pm.