This is not meant to be a scholarly work. There are no footnotes or index but there is a comprehensive contents list. Whether you read it all the way through or dip into it on an ad hoc basis, this is still a fascinating book.
There is a section on how not to get a good night's sleep and on the theories behind dreams and nightmares. There are snippetts about beds - design hasn't really changed since humans were invented and the origin of pyjamas - an Indian word. There are sections about sleep research and the effect of lack of sleep on the brain. There is also information about how animals sleep - in the case of dolphins with one side of the brain at a time.
I found it very interesting and picked up lots of information I wasn't aware of before such as that lack of sleep is more dangerous than lack of food. It might not be the best gift for an insomniac friend but it would be a good buy for anyone who likes a lie in.