After controlling for several experimental design weaknesses of
prior studies, we found support for Baron’s (1990; Baron and
Thomley, 1994) theory that lighting can alter environmental
conditions enough to increase positive mood and decrease fatigue.
Two primary results supported this theory; first, we found
decreased depression scores at higher color temperatures, suggesting
that the valence dimension of mood can be enhanced
through higher color temperatures. This result is in line with
literature suggesting that higher color temperatures can mitigate
Seasonal Affective Disorder (SAD; Schweitzer et al., 2004). Second,
we found evidence that higher color temperatures produced an
increase in vigor/activity and decreased fatigue scores, allowing
participants to experience extended periods of arousal (wakefulness),
and as we demonstrate in the next section allow them to
perform faster on a series of cognitive tasks. Further, we note that
both of these effects appeared to be approximately linear; that is,
not only did the LED technology reduce depression and increase
arousal, but it did so most at the highest color temperatures. This
result directly supports research suggesting a positive association
between increased color temperature and enhanced mood and
arousal states (Erikson and Kuller, 1983; Wohlfarth and Gates,
1985).