LONDON (Reuters Life!) – Britons in their late 30s and early 40s are unhappier than any other age group, suffering from loneliness and depression as work and relationship pressures take their toll, according to a survey.

The research, by relationship advice charity Relate, found a fifth of those aged 35 to 44 wished they had a better relationship with their family, with nearly a third saying these relationships would improve if they could work fewer hours.

More than 20 percent of that age group said they felt lonely a lot of the time and five percent said they had no friends at all.

"Traditionally we associate the midlife crisis with people in their late 40s to 50s, but the report reveals that this period could be reaching people earlier than we would expect" said Claire Tyler, chief executive of Relate.

"It's when life gets really hard – you're starting a family, pressure at work can be immense and increasingly money worries can be crippling."

Relate found that 22 percent of 35 to 44-year-olds had suffered depression because of a bad relationship, and 40 percent had been cheated on by a partner.

The survey of 2,004 adults showed that, across all age groups, money worries and redundancies were the biggest strain on people's relationships with their partners, while communication problems, working long hours and the division of housework also put pressure on couples. The ways in which people communicate with their friends and family have changed with the growth of modern technology, the survey found.