An alarm clock that will not switch off until the slumberer has shown they are fully awake has been invented by a student at Strathclyde University.
The puzzle clock, created by Liam Hastie for his engineering degree, is designed to overcome "sleep inertia" - the groggy feeling which, scientists say, can impair mental faculties for ten minutes, but sometimes for up to two hours after waking.
The wall-mounted alarm clock can be switched off only when its user climbs out of bed, stands directly in front and repeats, by pressing coloured buttons, a sequence generated randomly each morning. If the user fails to repeat the sequence swiftly, the alarm will continue to blare until the task is completed correctly.
Mr Hastie, 23 - who designed a prototype as part of his degree course in design, manufacture and engineering management - was inspired by his own experience of repeatedly pressing the snooze button on his alarm as many as 20 times rather than getting up.
He said: "Alarm clocks are good at waking you - what they are not good at is actually getting you out of bed. Then I read about the concept of 'sleep inertia' and decided to invent an alarm clock that not only got you out of bed, but would only go off when you demonstrated that your pre-frontal cortex was actually online."