By Rachel Oakes
BBC TV's Sleep Clinic
Sleep is a warm, peaceful part of our lives unless, like one in five people in the UK, you suffer from a sleep disorder.
Jody was diagnosed with night terrors
Then sleep becomes a frightening or ear-splitting or unattainable thing that can push you and your relationships to the brink.
A new BBC One series follows several tired and bewildered sufferers, all desperate for a cure, as they undergo treatment in the biggest sleep clinic in the UK.
Jody Rothera, 29, had had a lifetime of terrifying nightmares in which she was being shot, stabbed or chased.
And she kept her boyfriend Jim awake at night with vivid hallucinations of creepy crawlies and even a pony cantering around the bedroom.
Jim said: "It's four times a night. You don't want to have a go at her because she can't help it, but in your head it is like 'I just want to sleep'."
Jody was booked into the Sleep Clinic for a complex overnight study to build a complete picture of her sleep.
After discounting night epilepsy, the clinic diagnosed "night terrors" - described as an emotional type of sleepwalking with a lot of anxiety and fear.
The doctors believe the problem could have stemmed from her parents' divorce when she was seven years old.
She has now been prescribed a drug to suppress her dreams when the problem is particularly bad.
Jody is glad she went to the clinic.
She said: "It has been quite an interesting journey really, from the beginning to understanding what on earth was happening and to now, where there is some sort of conclusion."
The clinic at Papworth Hospital in Cambridge ushers a staggering 3,000 narcoleptics, parasomniacs and chronic snorers through its doors each year, as well as diagnosing some of the rarest and most dangerous sleep disorders affecting the UK population.
Big part of life
Clinic Director Dr John Shneerson believes it is very strange that general medicine just concentrates on what happens during the daytime.
He said: "Why do doctors talk so much about what goes on when you're awake and ignore a third of people's lives? What we're doing is trying to get the balance back."
One of the clinic's specialisations is obstructive sleep apnoea, a condition where sleepers' throats flop shut, cutting off the oxygen supply.
This forces the body to continually wake up to kick-start breathing again.
The condition was diagnosed in David Lillistone, who is also a thunderous snorer.
"The next door neighbour heard me snoring through an 18-inch concrete wall," he said.
Now sleeping in a separate room from his wife Kim, David was given a machine to monitor his breathing which revealed the scale of the problem: "It said I stopped breathing 44 times an hour."
He had previously had no idea why he was so sleepy during the day, which was putting huge strain on his marriage.
Kim had begun to think David had lost interest in the marriage because he was always falling asleep when they were together.
The Sleep Clinic brought David in overnight to be fitted with a Continuous Positive Airway Pressure mask.
This blows pressurised air through the airways keeping them continually open during sleep.
This produced instant results - and David had his first continuous night's sleep in years. It also cured his mighty snore.
They are back in the same bed again now and David said: "I feel like a new fella. It is just like stepping back 10 years."
Kim agrees: "It's like being together for the first time again."
Sleep Clinic produced by Landmark Films is on Mondays, 2235 GMT, BBC One, repeated Tuesdays, 1930 GMT, BBC Two from week commencing 19 February.