Why would that be a bad sign? Every couple needs a bit of space once in a while, talking from experience as well.
You could use that time to do some exercise also because it seems like you've got a full-on lifestyle. Maybe it'll relax you a bit.
Ofcourse. Should be space to do things that are not bad.
I think husband and wife are One Body, so they shouldn't keep secrets if they are both True Believer and trust each others. I believe it's OK for a good wife to know why the husband stays awake around that time and vise versa.