Objective: We tested whether the effects of a dynamic lighting system are superior to conventional
lighting on emotions, agitation behaviour, quality of life, melatonin secretion and circadian restactivity
cycles in severely demented patients. As a comparison, an age matched control patient group was
exposed to conventional lighting. For none of the output measures were significant differences between
the two lighting conditions found during the 8 study weeks in fall/winter.
Methods: Thus, we divided the patient cohort (n = 89) into two groups, solely based on the median of
their daily individual light exposure. Patients with higher average daily light exposure (> 417 lx) showed
significantly longer emotional expressions of pleasure and alertness per daily observations than patients
with lower daily light exposure. Moreover, they had a higher quality of life, spent less time in bed, went
to bed later and initiated their sleep episodes later, even though the two groups did not differ with respect
to age, severity of cognitive impairment and mobility. In general, men were more agitated, had shorter
sleep with more wake episodes, had a lower circadian amplitude of relative rest-wake activity and interdaily
circadian stability than women. In particular, lower daily light exposures significantly predicted
lower circadian amplitudes of rest-activity cycles in men but not in women. This may indicate sex specific
susceptibility to daily light exposures for rest-activity regulation in older demented patients.
Results: Our results provide evidence that a higher daily light exposure has beneficial effects on emotions
and thus improved quality of life in a severely demented patient group.