Full Definition of MACHIAVELLIAN. 1. : of or relating to Machiavelli or Machiavellianism. 2. : suggesting the principles of conduct laid down by Machiavelli; specifically: marked by cunning, duplicity, or bad faith.
Sleep medicine is a subspecialty field in the US under several medical specialties including anesthesiology, internal medicine, family medicine, and neurology. Neurosurgery is a distinct specialty that involves a different training path, and emphasizes the surgical treatment of neurological disorders.
This makes sense, since melatonin is not a sleep hormone. It is a hormone with a wide range of physiological functions. Like I said, by playing a role in regulating our circadian rhythm, melatonin does tie into sleep patterns. But it does not induce sleep.