The stress of daily life has sparked a new phenomenon - sleep texting.
People with the rare condition send incoherent text messages while asleep to their friends and family - completely unaware that they are doing it.
Sleep specialist Dr David Cunnington, of Melbourne Sleep Disorder Centre in Australia, said patients had reported incidents of sleep texting - and he has advised people to leave their mobile phones outside the bedroom.
He said: 'We have had patients who have reported sending text messages to their friends and family while asleep.
'It is one of those things that happens, but it is very rare, and certainly not a common trend.'
Unsurprisingly, there are no studies into sleep texting - but a similar phenomenon, sleep emailing, was studied in 2008.
Researchers at the University of Toledo reported the case of a woman, 44, who would compose emails while sound asleep. She had no recollection of sending the emails when awake.
Dr Cunnington said cases of sleep emailing were more common, and were likely to have a more detrimental effect on the lives of sufferers.
Dr David Cunnington said people struggling to get a quality night's sleep should keep their phones out of the bedroom
He said: 'Emails can be sent to work colleagues and have much more serious consequences, whereas text messages are more likely to be accidentally sent to a friend or family member, so people aren't as likely to complain of a problem.'