Many of the 350,000 carers across Wales feel isolated and exhausted by their work, research to mark the start of National Carers Week has shown.
A survey found carers believed their role was affecting their relationships and they needed more support.
The Welsh Assembly Government announced an extra £1m per year for carers' services in March.
Around 3,500 declared carers responded to the survey by post and online between January and April 2007.
Two-thirds of carers in Wales said their relationships had suffered as a direct result of their caring responsibilities.
Of those adversely affected, six in 10 said they missed out on quality time with their partners.
And the survey showed that when carers in Wales did get time to relax, almost a quarter (23%) used it to catch up on their sleep, with a further 27% using the opportunity to carry out chores.
The statistics are part of a nationwide survey and looked in detail at carers' feelings about a range of issues, including finances, career, health and relationships.
This is the thirteenth annual Carers Week, jointly organised by seven UK-wide charities including Carers UK, Counsel and Care, Crossroads Caring for Carers, Macmillan Cancer Support, MS Society, Rethink and The Princess Royal Trust for Carers.
Events in Wales to mark the week range from a carers sports day to reflexology treatments and day trips to workshop sessions.
Bridgend Carers Centre has also organised a guided walk of local nature reserve Parc Slip in Aberkenfig.
Doris Dalimore, centre manager, said: "Carers in Wales really are unsung heroes.
"Their hard work is unpaid and their own needs often go unnoticed.
"We know of approximately 350,000 carers in Wales, but many others struggle alone and do not realise that help is available to them," she added.
"Carers Week aims to raise greater awareness of the support and encourage people to access it."