Will it be ok for me to go to sleep now?

[ImUsuallyThisQuiet]

Just had a heavy book fall on my head. I know with children it's advisable to keep them awake for some time to keep an eye on them.

Yes I would

They no longer advise keeping children awake as long as no nausea or vomiting, you should be fine

www.nhs.uk/conditions/head-injury-and-concussion/

If you were reading and it fell on your face - 99.999% you are fine - even if the corner hit you/
If it fell, (or was thrown) from a few feet/metres away and it hit you spine first, and you blacked out or are feeling dizzy then, maybe, get it checked (but I probably wouldn't)

Did you lose consciousness? Do you have a headache, dizziness, nausea? If the answer is no then you’re likely fine!