http://precedings.nature.com/tags/sleep Recently posted documents tagged with 'sleep' Nature Publishing Group en Nature Precedings http://precedings.nature.com/images/header_logo.gif http://precedings.nature.com http://precedings.nature.com/documents/2964/version/1 Human sleep patterns differ across age groups and between males and females, and their association with age and gender suggest that they might have been the target of sexual selection during human evolutionary history. In this study, I will test the hypothesis that a phase-delayed circadian phase is a sexually selected trait in humans. A short version of the Horne and Ostberg questionnaire and a questionnaire on sexual behaviour were administered to 134 males and 140 females. A significant negative relationship was found between the MEQ score and the number of sexual partners among males, with evening types reporting more sexual partners than morning types. No significant relationship between females MEQ and number of sexual partners was found. Findings support the hypothesis that evening preference in males is a sexually selected trait. http://precedings.nature.com/documents/2964/version/1 Tue, 31 Mar 2009 14:55:17 UTC Circadian Preference and Sexual Selection: A Novel Evolutionary Approach hdl:10101/npre.2009.2964.1 2009-03-31 Davide Piffer Nature Precedings 2009-03-31T14:55:17Z Manuscript Evolutionary Biology http://creativecommons.org/licenses/by/3.0/ http://precedings.nature.com/documents/2342/version/1 Background: Weight loss can be caused by a loss of body mass due to metabolism and by water loss as unsensible water loss, sweating, or excretion in feces and urine. Although weight loss during sleep is a well-known phenomenon, it has not yet been studied in relation to sleep structure or autonomic tonus during sleep. Our study is proposed to be a first step in assessing the relationship between overnight weight loss, sleep structure, and HRV (heart rate variability) parameters.Methods: Twenty-five healthy volunteers received a 487 kcal meal and 200 ml water before experiment. Volunteers were weighed before and after polysomnography. Absolute and relative weight indices were calculated. Time and frequency domain analysis of heart rate variability was assessed during stages 2, 4, and REM. Nonparametric linear regression analysis was performed between night weight loss parameters, polysomnographic, and HRV ariables. Results: HF correlated positively with weight loss during stage 4. Slow wave sleep duration correlated positively with weight loss and weight loss rate. The duration of Stage 2 correlated negatively with absolute and relative weight loss. Conclusions: Weight loss during sleep is dependent upon sleep stage duration and sleep autonomic tonus. Slow-wave sleep and sleep parasympathetic tonus may be important for weight homeostasis. http://precedings.nature.com/documents/2342/version/1 Tue, 30 Sep 2008 19:50:21 UTC Overnight weight loss: relationship with sleep structure and heart rate variability hdl:10101/npre.2008.2342.1 2008-09-30 Walter Moraes Nature Precedings 2008-09-30T19:50:21Z Manuscript Biotechnology Neuroscience http://creativecommons.org/licenses/by/3.0/ http://precedings.nature.com/documents/1195/version/1 We generated mice with a selective loss of GABAB receptors in orexin neurons. Orexin neurons in these GABAB1-/-(orexin) mice showed reduced responsiveness to GABAA receptor agonists due to a compensatory increase in GABAA receptor-mediated inhibition. This increased GABAA receptor-mediated inhibition of orexin neurons is due to orexin-1 receptor-mediated activation of local GABAergic interneurons. Surprisingly, orexin neurons were also less responsive to glutamate, apparently because the augmented GABAA receptor-mediated inhibition increases the membrane conductance and shunts excitatory currents. These observations indicate that absence of GABAB receptors decreases the sensitivity of orexin neurons to both excitatory and inhibitory inputs. GABAB1-/-(orexin)mice exhibited severe fragmentation of sleep/wake states during both the light and dark periods without affecting total sleep time or inducing cataplexy, indicating that GABAB receptors are crucial regulators of orexin neurons and that “fine tuning” of orexin neurons by inhibitory and excitatory inputs is important for the stability of sleep/waking states. http://precedings.nature.com/documents/1195/version/1 Mon, 01 Oct 2007 18:55:50 UTC Selective loss of GABAB receptors in orexin/hypocretin-producing neurons results in disrupted sleep/wakefulness architecture hdl:10101/npre.2007.1195.1 2007-10-01 Takeshi Sakurai Nature Precedings 2007-10-01T18:55:50Z Manuscript Neuroscience http://creativecommons.org/licenses/by/2.5/