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Author Cajochen, C.; Munch, M.; Kobialka, S.; Krauchi, K.; Steiner, R.; Oelhafen, P.; Orgul, S.; Wirz-Justice, A. url  doi
openurl 
  Title High sensitivity of human melatonin, alertness, thermoregulation, and heart rate to short wavelength light Type Journal Article
  Year 2005 Publication The Journal of Clinical Endocrinology and Metabolism Abbreviated Journal J Clin Endocrinol Metab  
  Volume (down) 90 Issue 3 Pages 1311-1316  
  Keywords Human Health; Adult; Body Temperature Regulation/physiology/*radiation effects; Circadian Rhythm/physiology/radiation effects; Color; Heart Rate/physiology/*radiation effects; Humans; *Light; Male; Melatonin/*metabolism; Retinal Cone Photoreceptor Cells/physiology; Sleep Stages/physiology/radiation effects; Wakefulness/physiology/*radiation effects  
  Abstract Light can elicit acute physiological and alerting responses in humans, the magnitude of which depends on the timing, intensity, and duration of light exposure. Here, we report that the alerting response of light as well as its effects on thermoregulation and heart rate are also wavelength dependent. Exposure to 2 h of monochromatic light at 460 nm in the late evening induced a significantly greater melatonin suppression than occurred with 550-nm monochromatic light, concomitant with a significantly greater alerting response and increased core body temperature and heart rate ( approximately 2.8 x 10(13) photons/cm(2)/sec for each light treatment). Light diminished the distal-proximal skin temperature gradient, a measure of the degree of vasoconstriction, independent of wavelength. Nonclassical ocular photoreceptors with peak sensitivity around 460 nm have been found to regulate circadian rhythm function as measured by melatonin suppression and phase shifting. Our findings-that the sensitivity of the human alerting response to light and its thermoregulatory sequelae are blue-shifted relative to the three-cone visual photopic system-indicate an additional role for these novel photoreceptors in modifying human alertness, thermophysiology, and heart rate.  
  Address Centre for Chronobiology, Psychiatric University Clinic, Wilhelm Kleinstr. 27, CH-4025 Basel, Switzerland. christian.cajochen@pukbasel.ch  
  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 0021-972X ISBN Medium  
  Area Expedition Conference  
  Notes PMID:15585546 Approved no  
  Call Number LoNNe @ kagoburian @ Serial 728  
Permanent link to this record
 

 
Author Lockley, S.W.; Brainard, G.C.; Czeisler, C.A. url  doi
openurl 
  Title High sensitivity of the human circadian melatonin rhythm to resetting by short wavelength light Type Journal Article
  Year 2003 Publication The Journal of Clinical Endocrinology and Metabolism Abbreviated Journal J Clin Endocrinol Metab  
  Volume (down) 88 Issue 9 Pages 4502-4505  
  Keywords Human Health; Adult; Area Under Curve; Circadian Rhythm/*radiation effects; Female; Humans; *Light; Male; Melatonin/*metabolism; Pineal Gland/metabolism/radiation effects; Saliva/metabolism; Non-programmatic  
  Abstract The endogenous circadian oscillator in mammals, situated in the suprachiasmatic nuclei, receives environmental photic input from specialized subsets of photoreceptive retinal ganglion cells. The human circadian pacemaker is exquisitely sensitive to ocular light exposure, even in some people who are otherwise totally blind. The magnitude of the resetting response to white light depends on the timing, intensity, duration, number and pattern of exposures. We report here that the circadian resetting response in humans, as measured by the pineal melatonin rhythm, is also wavelength dependent. Exposure to 6.5 h of monochromatic light at 460 nm induces a two-fold greater circadian phase delay than 6.5 h of 555 nm monochromatic light of equal photon density. Similarly, 460 nm monochromatic light causes twice the amount of melatonin suppression compared to 555 nm monochromatic light, and is dependent on the duration of exposure in addition to wavelength. These studies demonstrate that the peak of sensitivity of the human circadian pacemaker to light is blue-shifted relative to the three-cone visual photopic system, the sensitivity of which peaks at approximately 555 nm. Thus photopic lux, the standard unit of illuminance, is inappropriate when quantifying the photic drive required to reset the human circadian pacemaker.  
  Address Division of Sleep Medicine, Brigham and Women's Hospital, and Harvard Medical School, Boston, Massachusetts 02115, USA  
  Corporate Author Thesis  
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  Language English Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 0021-972X ISBN Medium  
  Area Expedition Conference  
  Notes PMID:12970330 Approved no  
  Call Number LoNNe @ kagoburian @ Serial 778  
Permanent link to this record
 

 
Author Weil, Z.M.; Borniger, J.C.; Cisse, Y.M.; Abi Salloum, B.A.; Nelson, R.J. url  doi
openurl 
  Title Neuroendocrine control of photoperiodic changes in immune function Type Journal Article
  Year 2014 Publication Frontiers in Neuroendocrinology Abbreviated Journal Frontiers in Neuroendocrinology  
  Volume (down) 37 Issue Pages 108-118  
  Keywords Animals; Photoperiod; Melatonin day length; Seasonality immune function; Neuroendocrine  
  Abstract Seasonal variation in immune function putatively maximizes survival and reproductive success. Day length (photoperiod) is the most potent signal for time of year. Animals typically organize breeding, growth, and behavior to adapt to spatial and temporal niches. Outside the tropics individuals monitor photoperiod to support adaptations favoring survival and reproductive success. Changes in day length allow anticipation of seasonal changes in temperature and food availability that are critical for reproductive success. Immune function is typically bolstered during winter, whereas reproduction and growth are favored during summer. We provide an overview of how photoperiod influences neuronal function and melatonin secretion, how melatonin acts directly and indirectly to govern seasonal changes in immune function, and the manner by which other neuroendocrine effectors such as glucocorticoids, prolactin, thyroid, and sex steroid hormones modulate seasonal variations in immune function. Potential future research avenues include commensal gut microbiota and light pollution influences on photoperiodic responses.  
  Address Department of Neuroscience, Ohio State University, Biomedical Research Tower #618, 460 West 12th Avenue, Columbus, OH, USA  
  Corporate Author Thesis  
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  Series Volume Series Issue Edition  
  ISSN 0091-3022 ISBN Medium  
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  Notes Approved no  
  Call Number IDA @ john @ Serial 1062  
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Author Bedrosian, Tracy A; Fonken, Laura K; Walton, James C; Haim, Abraham; Nelson, Randy J url  doi
openurl 
  Title Dim light at night provokes depression-like behaviors and reduces CA1 dendritic spine density in female hamsters Type Journal Article
  Year 2011 Publication Psychoneuroendocrinology Abbreviated Journal  
  Volume (down) 36 Issue 7 Pages 1062-1069  
  Keywords animals; Chronobiological effects; Behavior  
  Abstract The prevalence of major depression has increased in recent decades; however, the underlying causes of this phenomenon remain unspecified. One environmental change that has coincided with elevated rates of depression is increased exposure to artificial light at night. Shift workers and others chronically exposed to light at night are at increased risk of mood disorders,suggesting that nighttime illumination may influence brain mechanisms mediating affect. We tested the hypothesis that exposure to dim light at night may impact affective responses and alter morphology of hippocampal neurons. Ovariectomized adult female Siberian hamsters (Phodopus sungorus) were housed for 8 weeks in either a light/dark cycle (LD) or a light/dim light cycle (DM), and then behavior was assayed. DM-hamsters displayed more depression-like responses in the forced swim and the sucrose anhedonia tests compared with LD-hamsters. Conversely, in the elevated plus maze DM-hamsters reduced anxiety-like behaviors. Brains from the same animals were processed using the Golgi-Cox method and hippocampal neurons within CA1, CA3, and the dentate gyrus were analyzed for morphological characteristics. In CA1, DM-hamsters significantly reduced dendritic spine density on both apical and basilar dendrites, an effect which was not mediated by baseline cortisol, as concentrations were equivalent between groups. These results demonstrate dim light at night is sufficient to reduce synaptic spine connections to CA1. Importantly, the present results suggest that night-time low level illumination, comparable to levels that are pervasive in North America and Europe, may contribute to the increasing prevalence of mood disorders.  
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  Notes Approved no  
  Call Number LoNNe @ schroer @ Serial 1576  
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Author Wilhelm, I.; Born, J.; Kudielka, B.M.; Schlotz, W.; Wust, S. url  doi
openurl 
  Title Is the cortisol awakening rise a response to awakening? Type Journal Article
  Year 2007 Publication Psychoneuroendocrinology Abbreviated Journal Psychoneuroendocrinology  
  Volume (down) 32 Issue 4 Pages 358-366  
  Keywords Human Health; Adrenocorticotropic Hormone/blood; Adult; Arousal/*physiology; Circadian Rhythm; Humans; Hydrocortisone/blood/*metabolism; Hypothalamo-Hypophyseal System/physiology; Male; Pituitary-Adrenal System/physiology; Saliva/chemistry; Sleep/physiology  
  Abstract A distinct rise in cortisol levels that occurs after morning awakening is increasingly used as an indicator of adrenocortical activity which is associated with different pathologies. Although it was previously assumed that the transition from sleep to wake is essential for the occurrence of the cortisol morning rise, this has never been tested. Here, we examined 16 healthy young men (20-33 yrs) between 2300 and 0800 h under sleep laboratory conditions. Serum cortisol and plasma adrenocorticotropin (ACTH) as well as salivary cortisol levels (after subjects were woken up at 0700 h) were repeatedly assessed. In a supplementary study condition, salivary cortisol levels in the first hour after awakening were measured at the subjects' home on two consecutive days. Comparison of pre- and post awakening measurements revealed significantly steeper increases in cortisol and ACTH after awakening. The rise in cortisol upon awakening under laboratory conditions did not significantly differ from that observed at home. We conclude that the cortisol increase after awakening is a response to morning awakening that is distinct from the circadian rise in hypothalamo-pituitary-adrenal (HPA) activity in the morning hours. Although the cortisol awakening response is modulated by circadian influences, it primarily reflects phasic psychophysiological processes specific to the sleep-wake transition.  
  Address Department of Psychobiology, University of Trier, Johanniterufer 15, 54290 Trier, Germany  
  Corporate Author Thesis  
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  Language English Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 0306-4530 ISBN Medium  
  Area Expedition Conference  
  Notes PMID:17408865 Approved no  
  Call Number LoNNe @ kagoburian @ Serial 834  
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