If you have to work through a surprise stressful situation – say, oh just for example, a family member having major surgery* – it's very likely that you'll get short on sleep, or at least have somewhat disturbed sleep. You'll certainly be working yourself harder mentally and emotionally to bear this extra load along with whatever else is going on in your life.
You're gonna get stretched a little thin when it comes to restedness.
You may find that when the initial danger passes or when other people arrive to help take the load or after a week or so without relief, a lot of tension that you'd been fending off suddenly falls square onto you and you become exhausted and emotional. It's completely natural; don't feel bad.
Do the minimum you need to do that day and then go home. Eat something nourishing – stop for takeout if you need to – and drink some water or juice, then go to bed. Never mind it being before 8pm.
Here's the important part: if tomorrow is a workday, set your alarm clock right now.
It may be that you won't fall asleep right away, but that's okay. Don't watch TV. Just feel safe and cozy and read a bit. If you need it, you'll conk out soon and you may sleep for 10-12 hours. If you do, you needed it.
Charging your batteries is part of helping get you and the people you love through anything hard going on; don't try to get by without it.
*By the way, he came through great and is already enthusiastically on the mend.