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Author Vollmer, C.; Michel, U.; Randler, C.
Title Outdoor light at night (LAN) is correlated with eveningness in adolescents Type Journal Article
Year 2012 Publication Chronobiology International Abbreviated Journal Chronobiol Int
Volume 29 Issue 4 Pages 502-508
Keywords (up) Adolescent; *Adolescent Behavior/drug effects; Biological Clocks; Central Nervous System Stimulants/administration & dosage; *Circadian Rhythm/drug effects; Computers; Cross-Sectional Studies; Female; Germany; Humans; *Light; Lighting; Male; *Photic Stimulation; *Photoperiod; Questionnaires; *Sleep/drug effects; Television; Time Factors; Video Games; *Wakefulness/drug effects
Abstract External zeitgebers synchronize the human circadian rhythm of sleep and wakefulness. Humans adapt their chronotype to the day-night cycle, the strongest external zeitgeber. The human circadian rhythm shifts to evening-type orientation when daylight is prolonged into the evening and night hours by artificial light sources. Data from a survey of 1507 German adolescents covering questions about chronotype and electronic screen media use combined with nocturnal satellite image data suggest a relationship between chronotype and artificial nocturnal light. Adolescents living in brightly illuminated urban districts had a stronger evening-type orientation than adolescents living in darker and more rural municipalities. This result persisted when controlling for time use of electronic screen media, intake of stimulants, type of school, age, puberty status, time of sunrise, sex, and population density. Time spent on electronic screen media use-a source of indoor light at night-is also correlated with eveningness, as well as intake of stimulants, age, and puberty status, and, to a lesser degree, type of school and time of sunrise. Adequate urban development design and parents limiting adolescents' electronic screen media use in the evening could help to adjust adolescents' zeitgeber to early school schedules when they provide appropriate lighting conditions for daytime and for nighttime.
Address Department of Biology, University of Education Heidelberg, Germany. vollmer@ph-heidelberg.de
Corporate Author Thesis
Publisher Place of Publication Editor
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:22214237 Approved no
Call Number IDA @ john @ Serial 150
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Author Wood, B.; Rea, M.S.; Plitnick, B.; Figueiro, M.G.
Title Light level and duration of exposure determine the impact of self-luminous tablets on melatonin suppression Type Journal Article
Year 2013 Publication Applied Ergonomics Abbreviated Journal Appl Ergon
Volume 44 Issue 2 Pages 237-240
Keywords (up) Adolescent; *Computers, Handheld; Female; Humans; Light/*adverse effects; Male; Melatonin/*biosynthesis; Photoperiod; Saliva/*metabolism; Sleep/radiation effects; Time Factors; Young Adult; melatonin
Abstract Exposure to light from self-luminous displays may be linked to increased risk for sleep disorders because these devices emit optical radiation at short wavelengths, close to the peak sensitivity of melatonin suppression. Thirteen participants experienced three experimental conditions in a within-subjects design to investigate the impact of self-luminous tablet displays on nocturnal melatonin suppression: 1) tablets-only set to the highest brightness, 2) tablets viewed through clear-lens goggles equipped with blue light-emitting diodes that provided 40 lux of 470-nm light at the cornea, and 3) tablets viewed through orange-tinted glasses (dark control; optical radiation <525 nm approximately 0). Melatonin suppressions after 1-h and 2-h exposures to tablets viewed with the blue light were significantly greater than zero. Suppression levels after 1-h exposure to the tablets-only were not statistically different than zero; however, this difference reached significance after 2 h. Based on these results, display manufacturers can determine how their products will affect melatonin levels and use model predictions to tune the spectral power distribution of self-luminous devices to increase or to decrease stimulation to the circadian system.
Address Lighting Research Center, Rensselaer Polytechnic Institute, 21 Union Street, Troy, NY 12180, USA. woodb5@rpi.edu
Corporate Author Thesis
Publisher Place of Publication Editor
Language English Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0003-6870 ISBN Medium
Area Expedition Conference
Notes PMID:22850476 Approved no
Call Number IDA @ john @ Serial 136
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Author Ruger, M.; St Hilaire, M.A.; Brainard, G.C.; Khalsa, S.-B.S.; Kronauer, R.E.; Czeisler, C.A.; Lockley, S.W.
Title Human phase response curve to a single 6.5 h pulse of short-wavelength light Type Journal Article
Year 2013 Publication The Journal of Physiology Abbreviated Journal J Physiol
Volume 591 Issue Pt 1 Pages 353-363
Keywords (up) Adolescent; Adult; Body Temperature; Circadian Rhythm/*physiology; Female; Humans; *Light; Male; Melatonin/physiology; Young Adult; blue light; melatonin; photic response; whort-wavelength
Abstract The photic resetting response of the human circadian pacemaker depends on the timing of exposure, and the direction and magnitude of the resulting shift is described by a phase response curve (PRC). Previous PRCs in humans have utilized high-intensity polychromatic white light. Given that the circadian photoreception system is maximally sensitive to short-wavelength visible light, the aim of the current study was to construct a PRC to blue (480 nm) light and compare it to a 10,000 lux white light PRC constructed previously using a similar protocol. Eighteen young healthy participants (18-30 years) were studied for 9-10 days in a time-free environment. The protocol included three baseline days followed by a constant routine (CR) to assess initial circadian phase. Following this CR, participants were exposed to a 6.5 h 480 nm light exposure (11.8 muW cm(-2), 11.2 lux) following mydriasis via a modified Ganzfeld dome. A second CR was conducted following the light exposure to re-assess circadian phase. Phase shifts were calculated from the difference in dim light melatonin onset (DLMO) between CRs. Exposure to 6.5 h of 480 nm light resets the circadian pacemaker according to a conventional type 1 PRC with fitted maximum delays and advances of -2.6 h and 1.3 h, respectively. The 480 nm PRC induced approximately 75% of the response of the 10,000 lux white light PRC. These results may contribute to a re-evaluation of dosing guidelines for clinical light therapy and the use of light as a fatigue countermeasure.
Address Circadian Physiology Program, Division of Sleep Medicine, Brigham and Women's Hospital, Harvard Medical School, 221 Longwood Avenue, Boston, MA 02115, USA. mrueger@rics.bwh.harvard.edu
Corporate Author Thesis
Publisher Place of Publication Editor
Language English Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0022-3751 ISBN Medium
Area Expedition Conference
Notes PMID:23090946; PMCID:PMC3630790 Approved no
Call Number IDA @ john @ Serial 239
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Author Revell, V.L.; Molina, T.A.; Eastman, C.I.
Title Human phase response curve to intermittent blue light using a commercially available device Type Journal Article
Year 2012 Publication The Journal of Physiology Abbreviated Journal J Physiol
Volume 590 Issue Pt 19 Pages 4859-4868
Keywords (up) Adolescent; Adult; Circadian Clocks/physiology/*radiation effects; Female; Humans; *Light; Male; Melatonin/analysis/physiology; Saliva/chemistry; Young Adult; blue light
Abstract Light shifts the timing of the circadian clock according to a phase response curve (PRC). To date, all human light PRCs have been to long durations of bright white light. However, melanopsin, the primary photopigment for the circadian system, is most sensitive to short wavelength blue light. Therefore, to optimise light treatment it is important to generate a blue light PRC.We used a small, commercially available blue LED light box, screen size 11.2 x 6.6 cm at approximately 50 cm, approximately 200 muW cm(-2), approximately 185 lux. Subjects participated in two 5 day laboratory sessions 1 week apart. Each session consisted of circadian phase assessments to obtain melatonin profiles before and after 3 days of free-running through an ultradian light-dark cycle (2.5 h wake in dim light, 1.5 h sleep in the dark), forced desynchrony protocol. During one session subjects received intermittent blue light (three 30 min pulses over 2 h) once a day for the 3 days of free-running, and in the other session (control) they remained in dim room light, counterbalanced. The time of blue light was varied among subjects to cover the entire 24 h day. For each individual, the phase shift to blue light was corrected for the free-run determined during the control session. The blue light PRC had a broad advance region starting in the morning and extending through the afternoon. The delay region started a few hours before bedtime and extended through the night. This is the first PRC to be constructed to blue light and to a stimulus that could be used in the real world.
Address University of Surrey, Guildford, Surrey GU2 7XH, UK
Corporate Author Thesis
Publisher Place of Publication Editor
Language English Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0022-3751 ISBN Medium
Area Expedition Conference
Notes PMID:22753544; PMCID:PMC3487041 Approved no
Call Number IDA @ john @ Serial 345
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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 (up) 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
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