• Lewy, Alfred (PI)

Project: Research project

Project Details


Circadian phase position of normal subjects will be assessed by
measuring their plasma melatonin levels in the evening under dim
light to determine the nighttime onset of melatonin production by
the pineal gland (the dim light melatonin onset, or DLMO). As a
marker for circadian phase position, the DLMO appears to
accurately reflect the phase-shifting effects of light. These
phase-shifting effects will be evaluated in normals and compared
to patients suspected of having chronobiologic sleep and mood
disorders. Normal subjects will be studied on repeated occasions
in order to evaluate inter- and intrasubject variability, as well as
time of year effects. There will also be studies to define the
phase response curve in normals. Five types of patients will be
studied: advanced sleep phase syndrome, delayed sleep phase
syndrome, winter depression, unipolar depression and bipolar
depression. We propose to test four hypotheses: 1) intraindividual
variability in the DLMO can be decreased by a week of
standardized light-dark conditions; 2) human circadian rhythms
are regulated by bright light according to a phase response curve
similar to those described for other animals; 3) bright light is
more important than social cures in synchronizing human
circadian rhythms; and 4) phase advanced sleep and mood
disorders will respond to bright light in the evening and phase
delayed disorders will respond to bright light in the morning. We
propose to do seven experiments: 1) melatonin production and
response to light in normal subjects; 2) effect of social cues on
circadian rhythms in normal subjects; 3) effect of light pulses on
circadian rhythms in normal subjects; 4) - 6) treatment of
putatively chronobiologic sleep and mood disorders with
appropriately timed bright light; and 7) effect of shifting sleep on
circadian rhythms in normal subjects. These investigations should
help us decide how to optimally treat patients with bright light
and to identify patients with abnormally advanced and delayed
circadian rhythms.
Effective start/end date7/1/878/31/97


  • National Institutes of Health: $103,867.00
  • National Institutes of Health: $101,305.00
  • National Institutes of Health: $98,579.00
  • National Institutes of Health: $103,680.00


  • Medicine(all)


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