All the same, with kids, most of your days are your "off days" (not enough sleep or rest or energy), but you aren't really entitled to them. My solution has be

All the same, with kids, most of your days are your "off days" (not enough sleep or rest or energy), but you aren't really entitled to them. My solution has been to move to more of a supporting role (engineering manager, or architect or similar). Basically, if you are unavailable (as in not very productive), things still move along and happen, even if a bit suboptimally.