Yes, the peer pressure can be quite heavy. But just go back early if you have to and psycho others to do so too so you won't be the only one to get singled out by seniors.

In the end you have to decide which is worse: the psychological stress from being criticized by your teammates and seniors, or that from staying in office much longer than you'd like.

Unless your position now has a very good promise of promotion or increment of pay, or if you can't find some other job out there, I fail to see why you need to be enslaved this way by peer pressure (or competition to see who's the hardest working?).

Hmm, I OT (non paid) 1-2 hours every working day.. not because of peer pressure but because the management sets really tight schedules and I fear by working super hard (I come back on weekends sometimes...) I'm encouraging them to continue setting what may be eventually unrealisable project milestones and deliverables.

I've since 'compensated' by coming in late by 30 minutes...