Books for insomniacs

[Airmid]

I often wake up in the wee small hours and if I don't go back to sleep I get up, make a drink and read for half an hour or so. So, I'm looking for suggestions for books that are pick-up and put-downable; not too intense; that are reasonable intelligent and which I might end up leaving for a couple of weeks before I come back (ie. nothing too complicated where I'll forget the plot and characters).
Many thanks.

Would a book of short stories be suitable?

The George RR Martin books, the song of fire and ice. Short chapters, endless books.

I gave up on the George RR Martin books - way to many characters to keep straight in my head and showed no sign of coming to an end.

Something like the James Herriot Books? Or the Call the Midwife books?

Bill Bryson maybe?

"The Goblin Emperor" by Katherine Addison is low enough on the action that you can put it down after most chapters, but not sure about how complicated it is.

Bill Bryson is good for this or re-reading childhood favourites. Or I read jenni murray's history of the world in fifty women or something and that was good for this sort of
Thing.