We can't live without it, but it’s thought a third of us in the UK are simply not getting enough quality sleep. In fact, the problem has become so serious, it's been described as a 'major public health concern'.

Tonight's Fiona Foster meets people whose lives have become dominated by bad sleep, and investigates the causes and possible solutions.

So have we now become a nation of bad sleepers, and what should be done about it? Some experts believe that sleep has been left off of the agenda for too long.

Sleep is perhaps the primary mental health issue and needs to be addressed

Colin Espie, Sleep Expert

Rhianwen Gilmore from South Wales has suffered from night terrors for five years. She gets terrifying visions during the early stages of sleep, and wakes up screaming.

There's a man in extremely old fashioned clothing, top hat, cane, cloak, standing about three foot from the foot of my bed.... I wake up screaming the loudest scream you can imagine, absolutely shaking, petrified

Rhianwen Gilmore

Using night vision cameras Tonight captured evidence of Rhianwen's night terrors for a hospital to analyse, and hopefully treat.

Sleeping trouble is now the most widely reported psychological disorder in the UK. It's estimated that around twenty million of us could be suffering , affecting our personal lives and our performance at work.

Sleep problems are strongly correlated with depression, with anxiety and with stress. It is a major public health concern, I mean, if you've got a third of the population who aren't sleeping properly then they're not functioning, they're struggling with work... That's a major, major problem

Emily Wooster, Mental Health Foundation
Greg Shilton has sleep apnoea Credit: ITV / Tonight

Greg Shilton from Wednesbury in the West Midlands first developed sleep issues as a child, but what he had always thought of as just noisy snoring, was the symptom of a life threatening issue. Greg had severe sleep apnoea, and was stopping breathing 80 times an hour. He now uses a mask to keep his airway open whilst he sleeps.

Life is fantastic now.. I've been compliant on the machine for well over 18 months. The snoring has all but disappeared which my wife is delighted about, and everybody in my house is able to get a good night's sleep, including myself

Greg Shilton

With research suggesting that one in five teenagers have disturbed sleep due to technology, the problem is unlikely to go away, so how do we solve the problem of getting a good night’s sleep?

Why Can’t We Sleep?: Tonight is on ITV this evening at 7.30