An incurable condition causes a young woman to become paralysed when she wakes up – leaving her too scared to go to sleep.
Milly Agnew, 22, suffers from sleep paralysis, a condition which makes her unable to move or talk when she wakes up.
Episodes can last up to several minutes and they can occur while falling to sleep or waking up.
The online marketing account manager from Belsize Park, London, said: "You can’t even scream for help... It feels like I’m dying."
"Sometimes it will just happen when I’m lying next to someone," she explains. "It feels like I’m miles away."
"I try and move my head to be able to get myself out of it," she adds. "Friends have said it looks like I’m having a fit."
Sleep paralysis occurs when the mechanism that causes your muscles to relax during sleep temporarily persists after you've woken up.
Agnew first experienced the condition aged eight.
She said: “I was completely terrified. I was drifting to sleep then I felt it happen. I couldn’t move. I was trapped. It felt like half an hour but it could have been just minutes.
“I didn’t tell anybody because I didn’t understand what had happened.”
She said at first it happened rarely but gradually worsened.
“When I was younger it happened about twice in a year. But it progressively became worse as I got older."
Aged ten, she searched her symptoms on the internet.
Agnew said: “I found sleep paralysis on Google and knew that was it. But it was something no-one ever spoke about.
“I’d never heard of it before. I tried to ignore it.”
Aged 15, she was at the doctors about something else and mentioned her symptoms.
"They agreed it was sleep paralysis. They also said to try and get enough sleep," she says. "If you avoid going to sleep, it makes it worse. But I just wanted to stay awake so I didn’t have to go through it.”
Agnew will usually suffer from paralysis on consecutive nights. "I’ve had it 18 nights in a row before. The feeling of terror is horrendous. But I’ve had to get used to it."
Although she has attempted to track her sleep pattern it has not helped her to conquer the condition.
"I wrote down when it happened, how scary it was, how much sleep I had, what time I went to sleep.
"It just made me more aware but didn’t help.
"I can sometimes bring myself round by shaking my head.
"I just keep trying to move my head as much as possible.
"Then the rest of my body can move too.
"I try and speak too so strange sounds come out of my mouth."
Agnew now accepts there is not a cure for the condition.
She said: "I try and have an early night as much as possible.
"Stress makes it worse.
"So if something’s stressing me I write it down to get it all out."
The NHS said: "Sleep paralysis is a temporary inability to move or speak that happens when you're waking up or, less commonly, falling asleep.
"Although you're awake, your body is briefly paralysed, after which you can move and speak as normal. The paralysis can last from a few seconds to several minutes.
"Sleep paralysis doesn't cause you any harm, but being unable to move can be very frightening.
"Some people have sleep paralysis once or twice in their life, while others experience it a few times a month or more regularly."