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Author |
Gerrish, G.A.; Morin, J.G.; Rivers, T.J.; Patrawala, Z. |
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Title |
Darkness as an ecological resource: the role of light in partitioning the nocturnal niche |
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Journal Article |
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Year |
2009 |
Publication |
Oecologia |
Abbreviated Journal |
Oecologia |
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Volume |
160 |
Issue |
3 |
Pages |
525-536 |
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Keywords  |
Age Factors; Animals; Belize; Crustacea/*physiology; *Darkness; *Ecosystem; Feeding Behavior/physiology; Linear Models; Motor Activity/*physiology; Photoperiod; Sexual Behavior, Animal/physiology; Water Movements |
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Abstract |
Nocturnal behaviors that vary as a function of light intensity, either from the setting sun or the moon, are typically labeled as circadian or circalunar. Both of these terms refer to endogenous time-dependent behaviors. In contrast, the nightly reproductive and feeding behaviors of Vargula annecohenae, a bioluminescent ostracod (Arthropoda: Crustacea) fluctuate in response to light intensity, an exogenous factor that is not strictly time-dependent. We measured adult and juvenile activity of V. annecohenae throughout lunar cycles in January/February and June 2003. Overnight and nightly measurements of foraging and reproductive behavior of adult V. annecohenae indicated that activity was greatest when a critical “dark threshold” was reached and that the dark threshold for adult V. annecohenae is met when less than a third of the moon is visible or at the intensity of light 2-3 min before the start of nautical twilight when no moon is illuminated. Juvenile V. annecohenae were also nocturnally active but demonstrated little or no response to lunar illumination, remaining active even during brightly moonlit periods. In addition to light level, water velocity also influenced the behaviors of V. annecohenae, with fewer juveniles and adults actively foraging on nights when water velocity was high (>25 cm/s). Our data demonstrate that the strongest environmental factor influencing adult feeding and reproductive behaviors of V. annecohenae is the availability of time when illumination is below the critical dark threshold. This dependence on darkness for successful growth and reproduction allows us to classify darkness as a resource, in the same way that the term has been applied to time, space and temperature. |
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Department of Ecology and Evolutionary Biology, Cornell University, Ithaca, NY 14850, USA. ggerrish@nd.edu |
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0029-8549 |
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PMID:19330516 |
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IDA @ john @ |
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16 |
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Author |
Landers, J.A.; Tamblyn, D.; Perriam, D. |
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Title |
Effect of a blue-light-blocking intraocular lens on the quality of sleep |
Type |
Journal Article |
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Year |
2009 |
Publication |
Journal of Cataract and Refractive Surgery |
Abbreviated Journal |
J Cataract Refract Surg |
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Volume |
35 |
Issue |
1 |
Pages |
83-88 |
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Keywords |
Aged; Aged, 80 and over; Circadian Rhythm/physiology; Female; Humans; *Lens Implantation, Intraocular; *Lenses, Intraocular; Light; Male; *Phacoemulsification; Prosthesis Design; Questionnaires; Sleep/*physiology; blue light; sleep |
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Abstract |
PURPOSE: To evaluate whether implantation of a blue-light-blocking intraocular lens (IOL) affects sleep quality. SETTING: Repatriation General Hospital, Adelaide, Australia. METHODS: This study comprised patients who had bilateral cataract surgery during the preceding 12 months with implantation of a conventional SI40NB IOL or an AcrySof Natural SN60WF blue-light-blocking IOL. Patients were contacted by telephone at least 6 months after second-eye surgery, and the Pittsburgh Sleep Quality Index (PSQI) questionnaire was administered. Results were compared between groups. RESULTS: Of the 49 patients, 31 received conventional IOLs and 18, blue-light-blocking IOLs. The mean age of the patients was 80 years +/- 8.1 (SD). The median PSQI score was 6 (interquartile range 3 to 8). There were no statistically significant differences in PSQI scores between the 2 IOL groups (P = .65). This remained true after adjustment for sex, age, medication, and time since surgery. CONCLUSION: The blue-light-blocking IOL had no effect on the sleep quality of patients, indicating that these IOLs might serve as an alternative to conventional IOLs without a detrimental effect on circadian rhythm. |
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Department of Ophthalmology, Repatriation General Hospital, Adelaide, Australia. john.landers@bigpond.com |
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0886-3350 |
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PMID:19101429 |
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IDA @ john @ |
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288 |
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Schmoll, C.; Khan, A.; Aspinall, P.; Goudie, C.; Koay, P.; Tendo, C.; Cameron, J.; Roe, J.; Deary, I.; Dhillon, B. |
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Title |
New light for old eyes: comparing melanopsin-mediated non-visual benefits of blue-light and UV-blocking intraocular lenses |
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2014 |
Publication |
The British Journal of Ophthalmology |
Abbreviated Journal |
Br J Ophthalmol |
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Volume |
98 |
Issue |
1 |
Pages |
124-128 |
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Keywords |
Aged; Cataract/*physiopathology; Circadian Rhythm/physiology; Cognition/*physiology; Female; Humans; Lens Implantation, Intraocular; *Lenses, Intraocular; Light; Male; Phacoemulsification; Prospective Studies; Questionnaires; Reaction Time/physiology; Regression Analysis; Rod Opsins/*physiology; Sleep/*physiology; Physiology; Retina; blue blocker; blue light |
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BACKGROUND/AIMS: Melanopsin-expressing photosensitive retinal ganglion cells form a blue-light-sensitive non-visual system mediating diverse physiological effects including circadian entrainment and cognitive alertness. Reduced blue wavelength retinal illumination through cataract formation is thought to blunt these responses while cataract surgery and intraocular lens (IOL) implantation have been shown to have beneficial effects on sleep and cognition. We aimed to use the reaction time (RT) task and the Epworth Sleepiness Score (ESS) as a validated objective platform to compare non-visual benefits of UV- and blue-blocking IOLs. METHODS: Patients were prospectively randomised to receive either a UV- or blue-blocking IOL, performing an RT test and ESS questionnaire before and after surgery. Optical blurring at the second test controlled for visual improvement. Non-operative age-matched controls were recruited for comparison. RESULTS: 80 participants completed the study. Those undergoing first-eye phacoemulsification demonstrated significant improvements in RT over control (p=0.001) and second-eye surgery patients (p=0.03). Moreover, reduced daytime sleepiness was measured by ESS for the first-eye surgery group (p=0.008) but not for the second-eye group (p=0.09). Choice of UV- or blue-blocking IOL made no significant difference to magnitude of cognitive improvement (p=0.272). CONCLUSIONS: Phacoemulsification, particularly first-eye surgery, has a strong positive effect on cognition and daytime alertness, regardless of IOL type. |
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Princess Alexandra Eye Hospital, , Edinburgh, UK |
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0007-1161 |
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PMID:24158845 |
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IDA @ john @ |
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342 |
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Obayashi, K.; Saeki, K.; Iwamoto, J.; Ikada, Y.; Kurumatani, N. |
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Exposure to light at night and risk of depression in the elderly |
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Journal Article |
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Year |
2013 |
Publication |
Journal of Affective Disorders |
Abbreviated Journal |
J Affect Disord |
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Volume |
151 |
Issue |
1 |
Pages |
331-336 |
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Keywords |
Aged; Circadian Rhythm; Cross-Sectional Studies; Depression/*etiology; Female; Humans; Light/*adverse effects; Male; Melatonin/urine; Psychiatric Status Rating Scales; Risk Factors; Circadian rhythm; Daytime light; Depression; Elderly; Light at night; Melatonin; Mental Health |
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BACKGROUND: Recent advances in understanding the fundamental links between chronobiology and depressive disorders have enabled exploring novel risk factors for depression in the field of biological rhythms. Increased exposure to light at night (LAN) is common in modern life, and LAN exposure is associated with circadian misalignment. However, whether LAN exposure in home settings is associated with depression remains unclear. METHODS: We measured the intensities of nighttime bedroom light and ambulatory daytime light along with overnight urinary melatonin excretion (UME) in 516 elderly individuals (mean age, 72.8). Depressive symptoms were assessed using the Geriatric Depression Scale. RESULTS: The median nighttime light intensity was 0.8lx (interquartile range, 0.2-3.3). The depressed group (n=101) revealed significantly higher prevalence of LAN exposure (average intensity, >/= 5 lx) compared with that of the nondepressed group (n=415) using a multivariate logistic regression model adjusted for daytime light exposure, insomnia, hypertension, sleep duration, and physical activity [adjusted odds ratio (OR): 1.89; 95% confidence interval (CI), 1.10-3.25; P=0.02]. Consistently, another parameter of LAN exposure (duration of intensity >/= 10 lx, >/= 30 min) was significantly more prevalent in the depressed than in the nondepressed group (adjusted OR: 1.71; 95% CI, 1.01-2.89; P=0.046). In contrast, UME was not significantly associated with depressive symptoms. LIMITATION: Cross-sectional analysis. CONCLUSION: These results suggested that LAN exposure in home settings is significantly associated with depressive symptoms in the general elderly population. The risk of depression may be reduced by keeping nighttime bedroom dark. |
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Department of Community Health and Epidemiology, Nara Medical University School of Medicine, Nara, Japan. obayashi@naramed-u.ac.jp |
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0165-0327 |
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PMID:23856285 |
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IDA @ john @ |
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165 |
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Author |
Reddy, A.B.; O'Neill, J.S. |
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Title |
Healthy clocks, healthy body, healthy mind |
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Journal Article |
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2010 |
Publication |
Trends in Cell Biology |
Abbreviated Journal |
Trends Cell Biol |
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20 |
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1 |
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36-44 |
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Aging; Animals; Cell Cycle; *Circadian Rhythm; Humans; Neoplasms/genetics/metabolism; Signal Transduction |
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Circadian rhythms permeate mammalian biology. They are manifested in the temporal organisation of behavioural, physiological, cellular and neuronal processes. Whereas it has been shown recently that these approximately 24-hour cycles are intrinsic to the cell and persist in vitro, internal synchrony in mammals is largely governed by the hypothalamic suprachiasmatic nuclei that facilitate anticipation of, and adaptation to, the solar cycle. Our timekeeping mechanism is deeply embedded in cell function and is modelled as a network of transcriptional and/or post-translational feedback loops. Concurrent with this, we are beginning to understand how this ancient timekeeper interacts with myriad cell systems, including signal transduction cascades and the cell cycle, and thus impacts on disease. An exemplary area where this knowledge is rapidly expanding and contributing to novel therapies is cancer, where the Period genes have been identified as tumour suppressors. In more complex disorders, where aetiology remains controversial, interactions with the clockwork are only now starting to be appreciated. |
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Department of Clinical Neurosciences, University of Cambridge Metabolic Research Laboratories, Institute of Metabolic Science, Cambridge CB2 OQQ, UK. abr20@cam.ac.uk |
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0962-8924 |
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PMID:19926479; PMCID:PMC2808409 |
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IDA @ john @ |
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133 |
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