Science fiction. Aliens in space ship on long journey think their relaxing machines are fantasy. Read around 1963.

[James]

Book about 60 years old
Travellers in space ship use machines to enhance relaxation, but then one realises that they are affecting real beings and causing damage.
Book was stolen at this stage so have no idea what happened next!!

[Kris]

James, did you read this book around 1960? It's for adults not teens?

Can you describe the main characters, and where are they travelling from and to?

What do the alien travellers think the machines do? (Spoilers are okay in the comments. Just give us a clear warning before revealing a spoiler.)

[James]

Probably about 1963, Think there were three travellers on the ship.
One female, one of the males not nice!
To alleviate the boredom they use a machine which appears to let them enjoy another 'fantasy' world and do as they please.
One of the travellers begins to suspect that they are not fantasies and real beings are being hurt.
Sorry was a long time ago!!