Some patients are being transported hundreds of miles for treatment following a cut of 1,700 beds over the past two years.
One bipolar disorder patient from York was rushed 200 miles by ambulance to a London hospital at 3am because no bed was available in her area when she needed urgent care.
Other patients had to travel even further, with people being sent 300 miles from Devon to West Yorkshire and 240 miles from Oxford to Teesside.
The crisis in mental health care was exposed following a joint investigation by BBC News and the Community Care journal, using freedom of information requests.
The investigation found that the number of mental health patients in England travelling to seek emergency treatment has more than doubled in two years, reaching 3,024 in 2013-14.
One mental health trust spent £345,000 last year placing patients in bed-and-breakfast accommodation in order to free-up beds which were urgently needed by other patients.
Kent was one of the worst-hit areas, with 334 mental health patients sent out of the county at a cost of £5 million.
One patient was made to sleep on a mattress on the floor because no bed was available.
Mind charity chief executive Paul Farmer protested that continued cuts to funding were “taking a significant toll on the quality and availability of services.”
Rethink Mental Illness chief executive Mark Winstanley said: “It’s absolutely scandalous that people with serious mental health problems are being treated in such a terrible way.”