I tend to skim articles on health, but James Hamblin cracked me up with this throwaway bit here
The bed must be reserved as a place for sleep and sex only. That was the decree of psychologist Richard Bootzin in his influential 1972 proposal for a “stimulus-control” approach to better sleep. One central tenet was operant conditioning: The bed must be a sanctuary, such that the brain is trained to sleep when it is in the bed.
The allowance for sex—which, in its ideal form, is one of the most stimulating things a human body can experience—always seemed to me at odds with the stimulus-control approach. A note to aspiring self-help writers: The book For Better Sleep, Kitchen Sex remains unwritten. [link]