title: Spectral modulation of light wavelengths using optical filters: effect on melatonin secretion.
abstract: Shiftwork has been identified as a risk factor for various medical problems, such as cancer, heart disease, metabolic disturbances, depression, and anxiety disorders, and as reviewed this month, adverse reproductive function. Shiftwork misaligns physiological rhythms with respect to each other and to external environmental rhythms such as the 24-hour light/dark cycle. Light is the strongest time cue for entraining circadian rhythms in mammals, and aberrant light exposure patterns during shiftwork is one of the key factors that induce circadian misalignment. We have recently demonstrated, in both animal and clinical models, that filtering short wavelengths (below 480 nm) from nocturnal lighting can attenuate alterations in hormone secretion (melatonin and glucocorticoids) and in central and peripheral clock gene expression induced by nighttime light exposure. We also demonstrated that the use of optical filters led to an improvement in mood and in cognitive performance under controlled laboratory conditions and during field-based shiftwork studies. Moreover, there was an increase in sleep duration and quality on nights immediately following night shifts. We believe it is likely that optical filters incorporated into glasses or as coverings for light bulbs could be used as a method to improve or prevent many of the medical problems associated with circadian misalignment and rotating shiftwork.
authors.affiliation: Division of Reproductive Sciences, University of Toronto, Toronto, Ontario, Canada; Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, Toronto, Ontario, Canada; TCART Fertility Partners, Toronto, Ontario, Canada. Electronic address: casper@lunenfeld.ca.
authors.forename: Robert F
authors.initials: RF
authors.lastname: Casper
authors.affiliation: Division of Sleep and Circadian Disorders, Department of Neurology and Department of Medicine, Brigham and Women's Hospital; Division of Sleep Medicine, Harvard Medical School, Boston, Massachusetts.
authors.forename: Shadab
authors.initials: S
authors.lastname: Rahman
mesh_terms: D000818:Animals; D057906:Circadian Clocks / Q000528:radiation effects*; D002940:Circadian Rhythm / Q000528:radiation effects*; D006801:Humans; D008027:Light; D008550:Melatonin / Q000378:metabolism*; D017440:Photoperiod; D010789:Phototherapy / Q000379:methods*; D012890:Sleep / Q000528:radiation effects; D020178:Sleep Disorders, Circadian Rhythm / Q000378:metabolism / Q000503:physiopathology / Q000517:prevention & control*; D013997:Time Factors; D014940:Work Schedule Tolerance
chemical_list: D008550:Melatonin
keywords: Circadian rhythm; melatonin; night shifts; optical filters; shiftworkers; short wavelength light