He is a scientist emeritus and former chief of the Clinical Psychobiology branch of the National Institute of Mental Health (NIMH).
He subsequently completed his psychiatric residency at Yale School of Medicine and an internship at Michael Reese Hospital.
The onset of sleep was linked to a spike in the hormone melatonin, whose secretion by the brain's pineal gland is triggered by darkness.
Wehr and colleague Norman E. Rosenthal are credited with identifying and describing Seasonal Affective Disorder (SAD) and developing light therapy to treat it.
Wehr was the co-author of Circadian Rhythms in Psychiatry (Psychobiology and Psychopathology) with Frederick Goodwin, and How to Beat Jet Lag (1993) with D.A.