Looking for a novel, who’s title I thought was ‘Barnard’s Star’, but the hits with this name didn’t seem to fit. The novel is about an expedition to a star (could still be Barnard’s).
Plot points I remember: The drive was some kind of FTL that caused time reversal, with the effects being that the crew became younger and what was is more striking to my memory, the physics got time reversed: The crew were strapped to a centrifuge, and when it spun during the flight, the astronauts were flung toward the axis causing some injuries (I seem to remember that someone’s knees banged against their face).
Once arriving, they landed on a habitable planet and various tensions arose between the crew. Some of it was caused by political tension (the crew was multinational), and some due to the rejuvenation that the crew had experienced. For example, the American astronaut in the crew was known in his youth to be a skirt chaser, but had mellowed in middle age, but I guess the hormones of youth messed him up again and he started an affair with an east European female astronaut.
A memorable confrontation was a fight where the “medical laser” was used. This laser could produce short but rare (say once every minute) bursts of powerful light, So the protagonist feinted by using an ordinary flashlight to spoof his (her?) adversary. The book must be at least 30 years old, and the bit with the centrifuge makes me think it was written after Kubrick/Clark popularized the concept, so 1970-1990ish.