Seven in 10 families caring for someone with severe learning disabilities are close to or has reached breaking point, a survey suggests.
Families are close to breaking point, the poll says
Charity Mencap is calling for councils to give every family caring for an adult or child with severe learning problems regular breaks.
The charity said a poll of 353 families in England and Northern Ireland showed 60% did not get the support needed.
Councils said they were doing the best they could with limited resources.
There are about 1.5m people with learning disabilities in the UK, although only 251,000 of these have conditions serious enough to qualify for disability living allowance.
This payment is given to the people with the most serious conditions, such as having a learning disability accompanied by either cerebral palsy, autism or epilepsy, that often require intensive care by their families.
There is no legal duty on councils to provide carers to relieve families of their responsibilities either for a few hours or overnight, although most local authorities do offer some sort of provision.
But the poll showed in the last year a third of families had experienced a cut in services.
Mencap called for the families with the greatest need - those on the highest rate of the allowance - to get a minimum of one break a week.
Those with slightly less serious conditions should either get fortnightly or monthly time off, the charity added.
It also wants local authorities to provide more information about the resources they have on offer.
Short breaks can involve people with learning disabilities going into respite care for a short period or carers coming into the person's home to allow their family to take a break.
Mencap chief executive Jo Williams said: "These families are falling to the back of the queue when it comes to funding and priority.
"Regular short-breaks in a safe, caring environment are vital and can make a huge difference to the quality of life of the whole family."
Emily Adams, who helps care for her 18-year-old grandson Duke in east London, said her local council does not offer any form of short break service.
"I have a feeling of permanent tiredness. It has affected my marriage, health, socialising, my thinking - you are constantly living not your life, but the life of somebody else.
"I can't carry on much longer and I shouldn't have to."
A spokesman for the Local Government Association said: "Mencap is quite right to point out that extra resources must be made available to ensure families can enjoy the breaks they need and deserve."
But he added councils were doing the best they could and the onus was on the government to "re-direct resources away from the acute sector and towards these community-based services".