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Author Gooley, J.J.; Rajaratnam, S.M.W.; Brainard, G.C.; Kronauer, R.E.; Czeisler, C.A.; Lockley, S.W.
Title Spectral responses of the human circadian system depend on the irradiance and duration of exposure to light Type Journal Article
Year 2010 Publication Science Translational Medicine Abbreviated Journal Sci Transl Med
Volume 2 Issue 31 Pages 31ra33
Keywords Adolescent; Adult; Circadian Rhythm/physiology/*radiation effects; Dose-Response Relationship, Radiation; Humans; Light; Melatonin/secretion; Photoperiod; Phototherapy; Retina/physiology/radiation effects; Retinal Cone Photoreceptor Cells/physiology/radiation effects; Retinal Ganglion Cells/physiology/radiation effects; Rod Opsins/physiology; Young Adult; blue light; light at night; melatonin; melanopsin; light therapy
Abstract In humans, modulation of circadian rhythms by light is thought to be mediated primarily by melanopsin-containing retinal ganglion cells, not rods or cones. Melanopsin cells are intrinsically blue light-sensitive but also receive input from visual photoreceptors. We therefore tested in humans whether cone photoreceptors contribute to the regulation of circadian and neuroendocrine light responses. Dose-response curves for melatonin suppression and circadian phase resetting were constructed in subjects exposed to blue (460 nm) or green (555 nm) light near the onset of nocturnal melatonin secretion. At the beginning of the intervention, 555-nm light was equally effective as 460-nm light at suppressing melatonin, suggesting a significant contribution from the three-cone visual system (lambda(max) = 555 nm). During the light exposure, however, the spectral sensitivity to 555-nm light decayed exponentially relative to 460-nm light. For phase-resetting responses, the effects of exposure to low-irradiance 555-nm light were too large relative to 460-nm light to be explained solely by the activation of melanopsin. Our findings suggest that cone photoreceptors contribute substantially to nonvisual responses at the beginning of a light exposure and at low irradiances, whereas melanopsin appears to be the primary circadian photopigment in response to long-duration light exposure and at high irradiances. These results suggest that light therapy for sleep disorders and other indications might be optimized by stimulating both photoreceptor systems.
Address Division of Sleep Medicine, Department of Medicine, Brigham and Women's Hospital, Boston, MA 02115, USA
Corporate Author Thesis
Publisher Place of Publication Editor (up)
Language English Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 1946-6234 ISBN Medium
Area Expedition Conference
Notes PMID:20463367 Approved no
Call Number IDA @ john @ Serial 294
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Author Sasseville, A.; Benhaberou-Brun, D.; Fontaine, C.; Charon, M.-C.; Hebert, M.
Title Wearing blue-blockers in the morning could improve sleep of workers on a permanent night schedule: a pilot study Type Journal Article
Year 2009 Publication Chronobiology International Abbreviated Journal Chronobiol Int
Volume 26 Issue 5 Pages 913-925
Keywords Adaptation, Physiological; Adult; Biological Clocks; Circadian Rhythm; Female; Humans; *Light; Male; Middle Aged; Photoperiod; Pilot Projects; Seasons; *Sleep; Wakefulness; *Work Schedule Tolerance; shift work; blue light; blue blocker; light therapy
Abstract Night shiftworkers often complain of disturbed sleep during the day. This could be partly caused by morning sunlight exposure during the commute home, which tends to maintain the circadian clock on a daytime rhythm. The circadian clock is most sensitive to the blue portion of the visible spectrum, so our aim was to determine if blocking short wavelengths of light below 540 nm could improve daytime sleep quality and nighttime vigilance of night shiftworkers. Eight permanent night shiftworkers (32-56 yrs of age) of Quebec City's Canada Post distribution center were evaluated during summertime, and twenty others (24-55 yrs of age) during fall and winter. Timing, efficacy, and fragmentation of daytime sleep were analyzed over four weeks by a wrist activity monitor, and subjective vigilance was additionally assessed at the end of the night shift in the fall-winter group. The first two weeks served as baseline and the remaining two as experimental weeks when workers had to wear blue-blockers glasses, either just before leaving the workplace at the end of their shift (summer group) or 2 h before the end of the night shift (fall-winter group). They all had to wear the glasses when outside during the day until 16:00 h. When wearing the glasses, workers slept, on average +/-SD, 32+/-29 and 34+/-60 more min/day, increased their sleep efficacy by 1.95+/-2.17% and 4.56+/-6.1%, and lowered their sleep fragmentation by 1.74+/-1.36% and 4.22+/-9.16% in the summer and fall-winter group, respectively. Subjective vigilance also generally improved on Fridays in the fall-winter group. Blue-blockers seem to improve daytime sleep of permanent night-shift workers.
Address Centre de Recherche Universite Laval Robert-Giffard/Department of Oto Rhino Laryngology and Ophtalmology, Universite Laval, Quebec, Canada
Corporate Author Thesis
Publisher Place of Publication Editor (up)
Language English Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0742-0528 ISBN Medium
Area Expedition Conference
Notes PMID:19637050 Approved no
Call Number IDA @ john @ Serial 295
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Author Bennett, S.; Alpert, M.; Kubulins, V.; Hansler, R.L.
Title Use of modified spectacles and light bulbs to block blue light at night may prevent postpartum depression Type Journal Article
Year 2009 Publication Medical Hypotheses Abbreviated Journal Med Hypotheses
Volume 73 Issue 2 Pages 251-253
Keywords Depression, Postpartum/*prevention & control; *Eyeglasses; Female; Humans; *Lighting; blue light; light therapy; blue blocker
Abstract In 2001 it was discovered that exposing the eyes to light in the blue end of the visible spectrum suppresses the production of the sleep hormone, melatonin. New mothers need to get up during the night to care for their babies. This is the time when melatonin is normally flowing. Exposing their eyes to light can cut off the flow. It may also reset their circadian (internal) clock. On subsequent nights the melatonin may not begin flowing at the normal time making it difficult to fall asleep. Over time, disruption of the circadian rhythm plus sleep deprivation may result in depression. Women suffering postpartum depression were enrolled in a small clinical trial. Some were provided with glasses and light bulbs that block blue light. Others were equipped with glasses and light bulbs that looked colored but did not block the rays causing melatonin suppression. Those with the “real glasses” recovered somewhat more quickly than those with the placebo glasses and light bulbs. The hypothesis that should be tested in large scale clinical trials is that the risk of postpartum depression can be reduced when a new mother avoids exposing her eyes to blue light when she gets up at night to care for her baby. In the meantime, all new mothers may benefit from using glasses and light bulbs that block blue light when getting up at night to care for their babies.
Address Postpartum Support, International P.O. Box 60931, Santa Barbara, CA 93160, USA
Corporate Author Thesis
Publisher Place of Publication Editor (up)
Language English Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0306-9877 ISBN Medium
Area Expedition Conference
Notes PMID:19329259 Approved no
Call Number IDA @ john @ Serial 296
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Author Kohyama, J.
Title A newly proposed disease condition produced by light exposure during night: asynchronization Type Journal Article
Year 2009 Publication Brain & Development Abbreviated Journal Brain Dev
Volume 31 Issue 4 Pages 255-273
Keywords Adolescent; Adult; Biological Clocks; Child; Child, Preschool; Chronotherapy; Circadian Rhythm/physiology; Complementary Therapies; Humans; Infant; Japan; *Light; Motor Activity; Phototherapy; Serotonin/metabolism; Sleep; Sleep Disorders, Circadian Rhythm/*physiopathology/therapy; Students; Wakefulness
Abstract The bedtime of preschoolers/pupils/students in Japan has become progressively later with the result sleep duration has become progressively shorter. With these changes, more than half of the preschoolers/pupils/students in Japan recently have complained of daytime sleepiness, while approximately one quarter of junior and senior high school students in Japan reportedly suffer from insomnia. These preschoolers/pupils/students may be suffering from behaviorally induced insufficient sleep syndrome due to inadequate sleep hygiene. If this diagnosis is correct, they should be free from these complaints after obtaining sufficient sleep by avoiding inadequate sleep hygiene. However, such a therapeutic approach often fails. Although social factors are often involved in these sleep disturbances, a novel clinical notion--asynchronization--can further a deeper understanding of the pathophysiology of these disturbances. The essence of asynchronization is a disturbance in various aspects (e.g., cycle, amplitude, phase and interrelationship) of the biological rhythms that normally exhibit circadian oscillation, presumably involving decreased activity of the serotonergic system. The major trigger of asynchronization is hypothesized to be a combination of light exposure during the night and a lack of light exposure in the morning. In addition to basic principles of morning light and an avoidance of nocturnal light exposure, presumable potential therapeutic approaches for asynchronization involve both conventional ones (light therapy, medications (hypnotics, antidepressants, melatonin, vitamin B12), physical activation, chronotherapy) and alternative ones (kampo, pulse therapy, direct contact, control of the autonomic nervous system, respiration (qigong, tanden breathing), chewing, crawling). A morning-type behavioral preference is described in several of the traditional textbooks for good health. The author recommends a morning-type behavioral lifestyle as a way to reduce behavioral/emotional problems, and to lessen the likelihood of falling into asynchronization.
Address Department of Pediatrics, Tokyo Kita Shakai Hoken Hospital, 4-17-56 Akabanedai, Tokyo, Japan. j-kohyama@tokyokita-jadecom.jp
Corporate Author Thesis
Publisher Place of Publication Editor (up)
Language English Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0387-7604 ISBN Medium
Area Expedition Conference
Notes PMID:18757146 Approved no
Call Number IDA @ john @ Serial 297
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Author Thorne, H.C.; Jones, K.H.; Peters, S.P.; Archer, S.N.; Dijk, D.-J.
Title Daily and seasonal variation in the spectral composition of light exposure in humans Type Journal Article
Year 2009 Publication Chronobiology International Abbreviated Journal Chronobiol Int
Volume 26 Issue 5 Pages 854-866
Keywords Adolescent; Adult; Circadian Rhythm; Climate; Female; Genetic Variation; Humans; *Light; Male; Photochemistry/methods; Research Design; Rod Opsins/chemistry/genetics; *Seasons; Sleep
Abstract Light is considered the most potent synchronizer of the human circadian system and exerts many other non-image-forming effects, including those that affect brain function. These effects are mediated in part by intrinsically photosensitive retinal ganglion cells that express the photopigment melanopsin. The spectral sensitivity of melanopsin is greatest for blue light at approximately 480 nm. At present, there is little information on how the spectral composition of light to which people are exposed varies over the 24 h period and across seasons. Twenty-two subjects, aged 22+/-4 yrs (mean+/-SD) participated during the winter months (November-February), and 12 subjects aged 25+/-3 yrs participated during the summer months (April-August). Subjects wore Actiwatch-RGB monitors, as well as Actiwatch-L monitors, for seven consecutive days while living in England. These monitors measured activity and light exposure in the red, green, and blue spectral regions, in addition to broad-spectrum white light, with a 2 min resolution. Light exposure during the day was analyzed for the interval between 09:00 and 21:00 h. The time course of white-light exposure differed significantly between seasons (p = 0.0022), with light exposure increasing in the morning hours and declining in the afternoon hours, and with a more prominent decline in the winter. Overall light exposure was significantly higher in summer than winter (p = 0.0002). Seasonal differences in the relative contribution of blue-light exposure to overall light exposure were also observed (p = 0.0006), in particular during the evening hours. During the summer evenings (17:00-21:00 h), the relative contribution of blue light was significantly higher (p < 0.0001) (40.2+/-1.1%) than during winter evenings (26.6+/-0.9%). The present data show that in addition to overall light exposure, the spectral composition of light exposure varies over the day and with season.
Address Surrey Sleep Research Centre, Faculty of Health and Medical Sciences, University of Surrey, Guildford, Surrey, UK. helen.thorne@surrey.ac.uk
Corporate Author Thesis
Publisher Place of Publication Editor (up)
Language English Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0742-0528 ISBN Medium
Area Expedition Conference
Notes PMID:19637047 Approved no
Call Number IDA @ john @ Serial 298
Permanent link to this record