scholarly journals The circadian system alters thermoregulation depending on the time of day and feeding condition

2009 ◽  
Author(s):  
Kei Nagashima ◽  
Ken Tokizawa ◽  
Yuki Uchida
Keyword(s):  
Time Of Day ◽  
Circadian System ◽  
Feeding Condition

Biological Rhythmicity in Preterm Infants Prior to Discharge From Neonatal Intensive Care

PEDIATRICS ◽  
1995 ◽  
Vol 95 (2) ◽  
pp. 231-237
Author(s):  
Steven F. Glotzbach ◽  
Dale M. Edgar ◽  
Ronald L. Ariagno
Keyword(s):  
Heart Rate ◽  
Intensive Care ◽  
Preterm Infants ◽  
Rectal Temperature ◽  
Neonatal Intensive Care ◽  
Time Of Day ◽  
Circadian System ◽  
Physiological Variables ◽  
Postconceptional Age ◽  
The Impact

Objective. The study of biological rhythms and the influence of environmental factors in the timing and synchronization of different rhythmic events have important implications for neonatal health. Preterm infants in the neonatal intensive care unit (NICU) are deprived of the patterned influences of maternal sleep, temperature, heart rate, and hormonal cycles. The impact of the NICU and nursing interventions on the development of the circadian system was studied in 17 stable preterm infants in the Intermediate Intensive Care Nursery at Stanford University for three consecutive days at about 35 weeks postconceptional age. Outcome measurements. Rectal temperature, abdominal skin temperature, heart rate, and activity were simultaneously recorded at 2-minute intervals during each 3-day study by a small microcomputer (Vitalog). Results. Very low amplitude circadian rhythms were found for rectal and skin temperatures (maximum range 36.8 to 37.0°C); population mean values for heart rate (158 bpm) and activity (3.5 counts per 2-min bin) did not differ significantly as a function of time of day. Rectal temperature, averaged in 6-hour bins over the 24-hour day as a function of both postconceptional age and postnatal age, was significantly higher during the first part of the circadian cycle. In all infants, rhythmicity in each variable was dominated by ultradian periodicities that were coincident with feedings and related interventions; moreover, several physiological variables charted during feeding differed significantly from values obtained during periods in which caregiving interventions did not occur. Conclusion. Quantitative data on the preterm infant circadian system may facilitate evaluation of factors that improve therapeutic responses, recovery, and outcome of neonatal intensive care patients.

3. When timing goes wrong

2017 ◽  
pp. 24-44
Author(s):  
Russell G. Foster ◽  
Leon Kreitzman
Keyword(s):  
Circadian Rhythm ◽  
Time Of Day ◽  
Circadian System ◽  
Multiple Time ◽  
Sleep Phase ◽  
Circadian Rhythm Sleep Disorders ◽  
Time Zones ◽  
Delayed Sleep Phase Disorder ◽  
Delayed Sleep Phase ◽  
Delayed Sleep

While time of day, interacting with an individual’s chronotype, can have an important impact upon performance and health, severe disruption of the circadian system adds another level of complexity and severity. ‘When timing goes wrong’ considers the effects of flying across multiple time zones, resulting in jet lag, and shift work on human health. Sleep and circadian rhythm disruption is almost always associated with poor health. Four circadian rhythm sleep disorders have been identified: advanced sleep phase disorder, delayed sleep phase disorder, freerunning, and irregular sleep timing. Sleep and circadian rhythm disruption in mental illness and neurodegenerative disease is also discussed.

scholarly journals The Impact of Time of Day on Energy Expenditure: Implications for Long-Term Energy Balance

Nutrients ◽  
2019 ◽  
Vol 11 (10) ◽  
pp. 2383 ◽  
Author(s):  
Shaw ◽  
Leung ◽  
Jong ◽  
Coates ◽  
Davis ◽  
...  
Keyword(s):  
Energy Balance ◽  
Energy Expenditure ◽  
Energy Intake ◽  
Experimental Studies ◽  
Time Of Day ◽  
Circadian System ◽  
The Body ◽  
Energy Regulation ◽  
Meal Timing ◽  
The Impact

There is evidence to indicate that the central biological clock (i.e., our endogenous circadian system) plays a role in physiological processes in the body that impact energy regulation and metabolism. Cross-sectional data suggest that energy consumption later in the day and during the night is associated with weight gain. These findings have led to speculation that when, as well as what, we eat may be important for maintaining energy balance. Emerging literature suggests that prioritising energy intake to earlier during the day may help with body weight maintenance. Evidence from tightly controlled acute experimental studies indicates a disparity in the body’s ability to utilise (expend) energy equally across the day and night. Energy expenditure both at rest (resting metabolic rate) and after eating (thermic effect of food) is typically more efficient earlier during the day. In this review, we discuss the key evidence for a circadian pattern in energy utilisation and balance, which depends on meal timing. Whilst there is limited evidence that simply prioritising energy intake to earlier in the day is an effective strategy for weight loss, we highlight the potential benefits of considering the role of meal timing for improving metabolic health and energy balance. This review demonstrates that to advance our understanding of the contribution of the endogenous circadian system toward energy balance, targeted studies that utilise appropriate methodologies are required that focus on meal timing and frequency.

scholarly journals Circadian Control of Kisspeptin and a Gated GnRH Response Mediate the Preovulatory Luteinizing Hormone Surge

Endocrinology ◽  
2010 ◽  
Vol 152 (2) ◽  
pp. 595-606 ◽  
Author(s):  
Wilbur P. Williams ◽  
Stephan G. Jarjisian ◽  
Jens D. Mikkelsen ◽  
Lance J. Kriegsfeld
Keyword(s):  
Neural Circuit ◽  
Time Of Day ◽  
Circadian System ◽  
Cellular Activity ◽  
Lh Surge ◽  
Gating Mechanism ◽  
Circadian Control ◽  
Maximal Sensitivity ◽  
Luteinizing Hormone Surge ◽  
Daily Changes

Abstract In spontaneously ovulating rodents, the preovulatory LH surge is initiated on the day of proestrus by a timed, stimulatory signal originating from the circadian clock in the suprachiasmatic nucleus (SCN). The present studies explored whether kisspeptin is part of the essential neural circuit linking the SCN to the GnRH system to stimulate ovulation in Syrian hamsters (Mesocricetus auratus). Kisspeptin neurons exhibit an estrogen-dependent, daily pattern of cellular activity consistent with a role in the circadian control of the LH surge. The SCN targets kisspeptin neurons via vasopressinergic (AVP), but not vasoactive intestinal polypeptide-ergic, projections. Because AVP administration can only stimulate the LH surge during a restricted time of day, we examined the possibility that the response to AVP is gated at the level of kisspeptin and/or GnRH neurons. Kisspeptin and GnRH activation were assessed after the administration of AVP during the morning (when AVP is incapable of initiating the LH surge) and the afternoon (when AVP injections stimulate the LH surge). Kisspeptin, but not GnRH, cellular activity was up-regulated after morning injections of AVP, suggesting that time-dependent sensitivity to SCN signaling is gated within GnRH but not kisspeptin neurons. In support of this possibility, we found that the GnRH system exhibits pronounced daily changes in sensitivity to kisspeptin stimulation, with maximal sensitivity in the afternoon. Together these studies reveal a novel mechanism of ovulatory control with interactions among the circadian system, kisspeptin signaling, and a GnRH gating mechanism of control.

Let there be blue-depleted light: in-patient dark therapy, circadian rhythms and length of stay

2020 ◽  
pp. 1-12 ◽  
Author(s):  
Jan Scott ◽  
Knut Langsrud ◽  
Ingunn Ro Goulding ◽  
Havard Kallestad
Keyword(s):  
Circadian Rhythms ◽  
Sleep Disturbances ◽  
Light Exposure ◽  
Environmental Influence ◽  
Time Of Day ◽  
Circadian System ◽  
Temporal Organization ◽  
Night Time ◽  
Inpatient Psychiatric Care ◽  
The Impact

SUMMARY Light is the most important environmental influence (zeitgeber) on the synchronization of the circadian system in humans. Excess light exposure during the evening and night-time affects secretion of the hormone melatonin, which in turn modifies the temporal organization of circadian rhythms, including the sleep–wake cycle. As sleep disturbances are prominent in critically ill medical and psychiatric patients, researchers began to examine the impact of light exposure on clinical outcomes and length of hospitalization. In psychiatric inpatients, exposure to bright morning light or use of blue blocking glasses have proved useful interventions for mood disorders. Recently, knowledge about light and the circadian system has been applied to the design of inpatient facilities with dynamic lighting systems that change according to time of day. The installation of ‘circadian lighting’ alongside technologies for monitoring sleep–wake patterns could prove to be one of the most practical and beneficial innovations in inpatient psychiatric care for more than half a century.

scholarly journals Nutrition and the circadian system

2016 ◽  
Vol 116 (3) ◽  
pp. 434-442 ◽  
Author(s):  
Gregory D. M. Potter ◽  
Janet E. Cade ◽  
Peter J. Grant ◽  
Laura J. Hardie
Keyword(s):  
Environmental Changes ◽  
Time Of Day ◽  
Circadian System ◽  
Suprachiasmatic Nuclei ◽  
Peripheral Tissues ◽  
Physiological Processes ◽  
Nutritional Science ◽  
High Fat Diets ◽  
Nutritional Compounds ◽  
Fat Diets

AbstractThe human circadian system anticipates and adapts to daily environmental changes to optimise behaviour according to time of day and temporally partitions incompatible physiological processes. At the helm of this system is a master clock in the suprachiasmatic nuclei (SCN) of the anterior hypothalamus. The SCN are primarily synchronised to the 24-h day by the light/dark cycle; however, feeding/fasting cycles are the primary time cues for clocks in peripheral tissues. Aligning feeding/fasting cycles with clock-regulated metabolic changes optimises metabolism, and studies of other animals suggest that feeding at inappropriate times disrupts circadian system organisation, and thereby contributes to adverse metabolic consequences and chronic disease development. ‘High-fat diets’ (HFD) produce particularly deleterious effects on circadian system organisation in rodents by blunting feeding/fasting cycles. Time-of-day-restricted feeding, where food availability is restricted to a period of several hours, offsets many adverse consequences of HFD in these animals; however, further evidence is required to assess whether the same is true in humans. Several nutritional compounds have robust effects on the circadian system. Caffeine, for example, can speed synchronisation to new time zones after jetlag. An appreciation of the circadian system has many implications for nutritional science and may ultimately help reduce the burden of chronic diseases.

scholarly journals Examination of zinc in the circadian system

2019 ◽  
Author(s):  
Mahtab Moshirpour ◽  
Amy S. Nakashima ◽  
Nicole Sehn ◽  
Victoria M. Smith ◽  
Richard H. Dyck ◽  
...  
Keyword(s):  
Retinal Ganglion Cells ◽  
Ganglion Cells ◽  
Time Of Day ◽  
Circadian System ◽  
The Body ◽  
Mouse Retina ◽  
List Type ◽  
Retinal Ganglion ◽  
Night And Day ◽  
Zinc Levels

ABSTRACTZinc is a trace element that is essential for a large number of biological and biochemical processes in the body. In the nervous system zinc is packaged into synaptic vesicles by the ZnT3 transporter, and synaptic release of zinc can influence the activity of postsynaptic cells, either directly though its own cognate receptors, or indirectly by modulating activation of receptors for other neurotransmitters. Here, we explore the anatomical and functional aspects of zinc in the circadian system. Melanopsin-containing retinal ganglion cells in the mouse retina were found to colocalize ZnT3, indicating that they can release zinc at their synaptic targets. While the master circadian clock in the hamster suprachiasmatic nucleus (SCN) was found to contain, at best, sparse zincergic input, the intergeniculate leaflet (IGL) was found to have prominent zincergic input. Levels of zinc in these areas were not affected by time of day. Additionally, IGL zinc staining persisted following enucleation, indicating other prominent sources of zinc instead of, or in addition to, the retina. Neither enhancement nor chelation of free zinc at either the SCN or IGL altered circadian responses to phase-shifting light in hamsters. Finally, entrainment, free-running, and circadian responses to light were explored in mice lacking the ZnT3 gene. In every aspect explored, the ZnT3-KO mice were not significantly different from their wildtype counterparts. These findings highlight the presence of zinc in areas critical for circadian functioning but have yet to identify a role for zinc in these areas.HighlightsThe synaptic zinc transporter ZnT3 is found in melanopsin-containing retinal ganglion cells.While zinc input to the hamster SCN was found to be sparse at best, prominent zincergic staining was found throughout the IGL.Zinc levels in the SCN and IGL did not change between the night and day.Neither increasing nor decreasing zinc levels in either the SCN or IGL had an influence on circadian responses to light.Mice lacking the ZnT3 transporter did not differ from wildtype mice on a wide variety of circadian measures.

Sign in / Sign up

Export Citation Format

Share Document