Social isolation can be made worse by living in a cold home, according to NHS Highland and Home Energy Scotland.
They say that older people are particularly vulnerable, and high levels of fuel poverty across Highland add to the problem.
Cathy Steer, head of health improvement at NHS Highland, said: “High fuel bills may prevent people from going out as they are worried about getting cold outside, then returning to an already cold home.
“People who are unable to keep their homes warm may also be reluctant to invite friends or neighbours to visit.”
The health board recently launched its “Reach Out” campaign in which people are urged to sign a pledge committing them to do something to make others less lonely.
Bob Grant, manager of Home Energy Scotland’s Highlands and islands advice centre added: “According to the 2012-14 Scottish House Condition Survey, 72% of Highland pensioners were classed as living in a fuel-poor household, and the day-to-day effect of fuel poverty can be stark.
“Our advisers speak with people who move into one room during the winter as they cannot afford to heat the rest of their house. We’ve helped clients who don’t even switch on their lights because they are worried about their bills.”
Anyone needing advice should contact Home Energy Scotland on 0808 808 2282.