An observation by Robert Vorona at Sentara Norfolk General Hospital in Virginia has led to the discovery that chocolate could promote violent sleep disorders in men.

Vorona first noticed the link while studying a patient, and a survey recently published in New Scientist magazine explains that the caffeine in chocolate could prevent the body producing the natural chemicals that enable paralysis during sleep.

About one person in 2000 suffers from a rapid eye movement (REM) sleep behaviour disorder, unknowingly acting out their dreams and thrashing about in bed.