I recommend Before I go to Sleep: A Novel by S. J. Watson.  Seems I have been reading books about brain function lately.  This one was terrifying and also extremely hard to put down.  Amazing plot and very well put together. 

This woman has a brain injury, wakes up in the hospital and can't remember anything at all.  She gathers information but when she sleeps she loses it all and must start over.  Her husband is very helpful in helping her adjust to her new life...and she starts to keep a journal so she can read what she has learned each morning and not have to start fresh.  The plot thickens!!!

A great read for summer...or on an airplane as there are no airplane crashes in the thing at all! 

Just for enjoyment...
Linda