Nearly identical situation, newborn kid. I'm at a place now where working 40 hours a week is not unusual or looked down upon. It's still a successful web comp

Nearly identical situation, newborn kid. I'm at a place now where working 40 hours a week is not unusual or looked down upon. It's still a successful web company. I ended up here having worked anywhere from 50-100 hour weeks in academia, by following the "deathbed principle:" when deciding whether to do X, imagine yourself on your deathbed, and decide if you would wish you had done X or more of X. It puts things nicely in perspective. I now sleep well at night (well, kid permitting) and don't feel bad about not killing myself with work. There are certainly coworkers who work more hours, and no doubt they will get better bonuses/promotions but that's fine by me.