If your workplace is suffering from a ‘long hours culture’, it should still be perfectly possible to work your proper hours, go home on time and still get your work done. After all, you are judged by your performance, not your presence. However, the peer pressure is unlikely to go away unless you take steps to change the culture.
Since it’s irrational and unproductive to stay at work for the sake of it, most managers are likely to believe, in principle at least, in working productively and leaving on time. Arrange with your colleagues (safety in numbers!) to raise the issue constructively in a team meeting (if you are worried about how your manager will react, you could think about having a union rep do it with you).
Find out if there is some historical reason that this culture has crept up on you. In many jobs, there may be a need to work harder and for longer hours every so often. There may be emergencies or big deadlines when you are temporarily required to put in extra time, but these are the exception and shouldn’t become the norm. If your boss says the office needs to be manned until late on a regular basis, suggest a rota – not everyone needs to be there.
Once you have broken the silence on sensible hours, it’s time to walk the talk. Make sure you leave at a reasonable time each day and encourage your colleagues to do so too. If there are brownie points for being the last person in the office, then all leave at the same time. If people who skip lunch curry favour – then all go out for lunch together. Start doing it once a week. Ask the boss too. Make your point and stick to it and, with a bit of luck, attitudes will begin to change.