Chronic artificial blue-enriched white light is an effective countermeasure to delayed circadian phase and neurobehavioral decrements

Raymond P. Najjar, Luzian Wolf, Jacques Taillard, Luc J. M. Schlangen, Alex Salam, Christian Cajochen, Claude Gronfier
PLoS ONE. 2014-07-29; 9(7): e102827
DOI: 10.1371/journal.pone.0102827

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1. PLoS One. 2014 Jul 29;9(7):e102827. doi: 10.1371/journal.pone.0102827.
eCollection 2014.

Chronic artificial blue-enriched white light is an effective countermeasure to
delayed circadian phase and neurobehavioral decrements.

Najjar RP(1), Wolf L(2), Taillard J(3), Schlangen LJ(4), Salam A(5), Cajochen
C(6), Gronfier C(1).

Author information:
(1)Inserm U846, Stem Cell and Brain Research Institute, Bron, France; University
of Lyon, Claude Bernard Lyon 1, Villeurbanne, France.
(2)Wolf Technologieberatung – Object-Tracker, Perchtoldsdorf, Austria.
(3)University of Bordeaux, Sommeil, Attention et Neuropsychiatrie, USR 3413,
Bordeaux, France; CNRS, Sommeil, Attention et Neuropsychiatrie, USR 3413,
Bordeaux, France.
(4)Philips Research, High Tech Campus 34 5656AE, Eindhoven, The Netherlands.
(5)Institut Polaire Français Paul-Emile Victor (IPEV), Technopôle Brest-Iroise –
BP 75, Plouzané, France.
(6)Centre for Chronobiology Psychiatric University Clinic, University of Basel,
Basel, Switzerland.

Studies in Polar Base stations, where personnel have no access to sunlight during
winter, have reported circadian misalignment, free-running of the sleep-wake
rhythm, and sleep problems. Here we tested light as a countermeasure to circadian
misalignment in personnel of the Concordia Polar Base station during the polar
winter. We hypothesized that entrainment of the circadian pacemaker to a 24-h
light-dark schedule would not occur in all crew members (n = 10) exposed to
100-300 lux of standard fluorescent white (SW) light during the daytime, and that
chronic non-time restricted daytime exposure to melanopsin-optimized
blue-enriched white (BE) light would establish an a stable circadian phase, in
participants, together with increased cognitive performance and mood levels. The
lighting schedule consisted of an alternation between SW lighting (2 weeks),
followed by a BE lighting (2 weeks) for a total of 9 weeks. Rest-activity cycles
assessed by actigraphy showed a stable rest-activity pattern under both SW and BE
light. No difference was found between light conditions on the intra-daily
stability, variability and amplitude of activity, as assessed by non-parametric
circadian analysis. As hypothesized, a significant delay of about 30 minutes in
the onset of melatonin secretion occurred with SW, but not with BE light. BE
light significantly enhanced well being and alertness compared to SW light. We
propose that the superior efficacy of blue-enriched white light versus standard
white light involves melanopsin-based mechanisms in the activation of the
non-visual functions studied, and that their responses do not dampen with time
(over 9-weeks). This work could lead to practical applications of light exposure
in working environment where background light intensity is chronically low to
moderate (polar base stations, power plants, space missions, etc.), and may help
design lighting strategies to maintain health, productivity, and personnel
safety.

DOI: 10.1371/journal.pone.0102827
PMCID: PMC4114570
PMID: 25072880 [Indexed for MEDLINE]

Auteurs Bordeaux Neurocampus