China
Africa
Explore chapters and articles related to this topic
Answers
Published in Ken Addley, MCQs, MEQs and OSPEs in Occupational Medicine, 2023
The suprachiasmatic nucleus in the hypothalamus has a key role in regulating circadian rhythms. The neocortex is the largest part of the cerebral cortex and is the outermost layer that covers the structures of the brain.
Circadian Rhythm
Published in Mehwish Iqbal, Complementary and Alternative Medicinal Approaches for Enhancing Immunity, 2023
Several physiological activities are controlled by internal body clocks, including sleep–wake cycles, metabolism, body temperature and feeding. Circadian activities fluctuate with a duration of 24 hours and can continue to fluctuate in the lack of entraining impetus. The clock in mammals is most frequently driven by light by means of input from the retina to the ‘master clock' or hypothalamus SCN (suprachiasmatic nucleus) (Brown & Piggins, 2007). Consumption of food, temperature and other consistently changing factors can also drive circadian behaviour. Under typical 12-hour cycles of darkness and 12-hour cycles of light, ZT0 (zeitgeber time) points out the duration at which lights of the sleeping area are switched on while ZT12 represents the time at which lights are switched off. Typically, humans are most active and alert during the phase of ‘daytime' after ZT0, while the animals who used to awaken at night are most active during the phase of ‘nighttime' subsequent to ZT12. If the elements of the circadian clock are complete and unimpaired, mammals are capable of sustaining strong circadian oscillations in physiological processes and activity for long durations even with the lack of rising stimuli (Downton et al., 2020; Takahashi, 2017).
Altitude, temperature, circadian rhythms and exercise
Published in Adam P. Sharples, James P. Morton, Henning Wackerhage, Molecular Exercise Physiology, 2022
Henning Wackerhage, Kenneth A. Dyar, Martin Schönfelder
The master circadian clock located in the suprachiasmatic nucleus, a small bundle of neurons in the hypothalamus of the brain. This master clock drives the ~24 h rhythm and is driven by ambient light sensed by specialised retinal ganglion cells in the back of the eye (i.e. light is the Zeitgeber, “time setter” of this clock).
The Effectiveness of a Multi-Sensory Sleep-Promotion Program on Sleep Quality among Hospitalized Older Adults of Thailand: A Quasi-Experimental Study
Published in Behavioral Sleep Medicine, 2023
Amornrat Kaewlue, Samoraphop Banharak, Ladawan Panpanit, Sutin Chanaboon
Poor quality sleep is frequently due to disturbances in a person’s surroundings, such as light and sound exposure (Kulpatcharapong et al., 2020). The external factors can be prevented by environmental management. For example, dimming lights at night promotes the suprachiasmatic nucleus to stimulate melatonin, which is a substance that relaxes the body, reduces anxiety, balances body temperature, and maintains the circadian rhythm (Arendt, 2006: Fuller et al., 2014; Panpanit, 2019; Srinivasan et al., 2009; Suthephakun, 2015). In addition, noise can cause changes in the heart rate, constrict the blood vessels, and inhibit rapid eye movement (REM) during sleep. These physiological changes lead to body alertness, sleep disturbance, and sleep loss (Fuller et al., 2014; Panpanit, 2019). The sleep of older adults is enhanced when the external environment is quiet, without disturbance, and in a comfortable position (Chusapalo, 2010). Similar to our findings, reducing noise and minimizing nighttime care activities improve sleep quality (Elmoneem & Fouad, 2017; Okamoto-Mizuno & Mizuno, 2012; Yodchai et al., 2007).
Theoretical construct into blocks of actigraphic-derived sleep parameters
Published in Chronobiology International, 2023
Letizia Galasso, Giovanna Calogiuri, Lucia Castelli, Antonino Mulè, Fabio Esposito, Andrea Caumo, Angela Montaruli, Eliana Roveda
The timing of nocturnal sleep is regulated by different neurochemical systems connected with each other, including the preoptic area and the suprachiasmatic nucleus, which receive afferences directly from retinal fibers (Buijs et al. 2003; Dijk and Lockley 2002; Sack 2009; Sothern et al. 2009). The suprachiasmatic nucleus is deemed as the main internal regulator of circadian rhythms and its degeneration can causes loss of entrainment with the daylight periodicity, the most important external synchronizer of the different rhythms (Buijs et al. 2003; Delaunay et al. 2000; Lee et al. 2000; Whitmore 2001), and desynchronization of endogenous behavioral and hormonal rhythms including the sleep-wake cycle. Hence, the endogenous rhythm of the sleep-wake cycle is, in normal conditions, synchronized with the alternation of day-night cycle, as well as other factors such as timing of meals and social routines. Such synchronization is important in order to maintain healthy sleep-wake patterns, as in fact its disruptions can lead to emergence of different sleep problems (Sack et al. 2007a, 2007b).
Choroid plexus and CSF: an updated review
Published in British Journal of Neurosurgery, 2022
Dana Hutton, Mohammed Gadoora Fadelalla, Avinash Kumar Kanodia, Kismet Hossain-Ibrahim
Circadian rhythms control various physiological functions, such as hormone secretion, blood pressure and body temperature regulation.37 The suprachiasmatic nucleus (SCN) is deemed the ‘master clock’ of these rhythms. Its action is influenced by other ‘peripheral clocks’, termed circadian oscillators. Yamaguchi et al. proposed the ChP is functional as an intrinsic oscillator, and can influence the SCN. The group observed the rPer1*, rPer2** and rBmal1*** expression in the ChP of the lateral and fourth ventricles of male rats to be of a circadian manner. This pattern of expression is seen in the SCN and the pineal gland (PG)-regions known to exhibit circadian oscillator function.37 Interaction between the ChP, PG and SCN (intrinsic oscillators) is thought to maintain a stable 24hr circadian rhythm. The ChP was found to have a short intrinsic circadian period (∼21hrs). The authors were unable to explain this, but casein kinase I ε/δ is thought to play some role.37 Further studies are required to address this.