34 Another study showed that sustained pupil contraction to a bright blue light stimulus

increased, and redilation to baseline took longer, in older than younger subjects.35 This may indicate a compensatory response to the lower blue light transmission through the aging lens. The fact that older patients with cataracts exhibited faster reaction times under blue-enriched light after cataract surgery (with clear UV-only blocking intraocular lens replacement) when compared with presurgery performance36 indicates that attenuation of blue light sensitivity might be an epiphenomenon caused by Epacadostat reduced light transmission of the lens, and not by a change in sensitivity Inhibitors,research,lifescience,medical of melanopsin-dependent function itself. Likewise, older subjects suppressed melatonin less in response to monochromatic blue than green light37,38 and exhibited reduced responsiveness with respect to mood and alertness when compared with a young group.37 Healthy older subjects showed a reduction in the phase-delaying Inhibitors,research,lifescience,medical response to moderate light39 and, evening exposure of healthy elderly subjects to either polychromatic blue-enriched or polychromatic white light did not differ in its effects on phase delay, evening alertness, and sleep architecture.40 One interpretation might be

that non-image-forming light perception Inhibitors,research,lifescience,medical undergoes different age-related modifications of functionally separated ipRGC dependent pathways. Light treatment of misaligned circadian rhythms Scheduled bright light exposure is an effective countermeasure for sleepiness and fatigue, ie, in shift workers during night work and for re-entrainment after return to daytime shifts, Inhibitors,research,lifescience,medical or jet lag. Other circadian

rhythm sleep disorders, such as delayed and advanced sleep phase syndrome, can be treated with light therapy as well (for reviews see refs 41,42). Light therapy is used alone or as adjuvant Inhibitors,research,lifescience,medical therapy in a growing number of psychiatric and neurodegenerative diseases, where alterations of sleep-wake cycles are often observed:43-45 Light has antidepressant properties and is the treatment of choice for seasonal affective disorder (SAD),46 and is increasingly used in nonseasonal depression,45-47 particularly efficient when combined with serotonin reuptake inhibitors.48-50 Moreover, beneficial effects of light on mood, agitation, sleep quality, and/or cognitive performance have been found in patients Idoxuridine with ante-partum depression,51 borderline personality disorder,52,53 bulimia nervosa,54 adult attention-deficit/hyperactivity disorder,55 and Parkinson’s disease56 as well as Alzheimer’s disease and other dementias,57,58 by applying open trial designs and double-blind protocols. The control condition in those studies was either no light treatment, or lower light intensities (ie, 70 lx,51 500 lx red light54), or lower lighting (±300 lx) compared with whole-day bright lighting installations (±1000 lx) in elderly care units.