> I've always said to insomniacs that they should read textbooks.

I'm not a good sleeper and quite like reading. If I'm in a state where I'm very tired but also having trouble getting off to sleep then I'm generally too tired to read. I may be able to manage a paragraph or two before my eyes start to lose focus but that's it.

I'm not wide awake and fully functioning, I'm lying there tired but unable to get off to sleep - these are quite different states.

The best thing I can do is to close my eyes and build 3D models in my head and fly around them. That sometimes helps, I think it concentrates the mind.