DP is from Spain, and in July we spent ten days at his parents, our first stay there since DS was born in October. Of course, his parents' daily routine is completely different from ours - they have dinner at 9.30 pm at the earliest. This meant we were never in bed before 11 pm. Now, DS is in bed at 7 pm and wakes at 5.15-5.30 am, and in July he woke at least four times a night because he was teething. We were absolutely knackered with the lack of sleep and told ILs more than once that we usually go to bed at 9.30 pm, otherwise we are just exhausted the next day. They made absolutely no effort to have dinner earlier, not even by half an hour, instead telling us "DS is on holiday too, put him to bed later". I am aware that this is a cultural thing and that Spanish babies are put to bed much later, but AIBU to think it is pretty selfish to expect a baby to change its routine during a ten-day holiday?