Visual Attention is Modulated by Circadian Phase and the Sleep Homeostat

Nayantara Santhi, Ph.D.
Division of Sleep Medicine (Harvard Medical School)
Brigham & Women's Hospital

Our ability to attend to our environment is influenced by variations 
in alertness that occur throughout the day. Alertness is modified by 
many factors, two of the most important being the sleep homeostat 
(elapsed time awake) and the phase of the endogenous circadian 
pacemaker. Given that adverse circadian phase and elapsed time awake 
negatively affect alertness, one would expect that behavioral 
measures of attention would reflect this as well.  In this 
experiment, we studied circadian and time awake effects on 
attentional blink. There was a significant effect of circadian phase 
on attentional blink depth. Furthermore, there was a significant 
interaction between circadian phase and elapsed time awake on 
blinkdepth. These two results suggests that visual attention is 
modulated by the circadian pacemaker and the sleep homeostat.