Sleep Deprivation

Lunar Rhythms and Vertebrate Reproduction

Lunar rhythms in vertebrate reproduction are recurring reproductive events synchronized with moon-related environmental cycles, including monthly lunar, semilunar, and tidal periodicities.

Circadian Rhythm Networks Regulate Systemic Metabolic Homeostasis

Circadian rhythm networks form an endogenous timing system that organizes metabolism across the approximately 24-hour day.

Genetic-Circadian Interaction Regulates Metabolic Homeostasis in Obesity

Circadian regulation of metabolic homeostasis describes the genetic timekeeping network that aligns energy intake, substrate utilization, endocrine activity, and tissue metabolism with the approximately 24-hour environmental cycle.

Regulation of Cognitive Function by Cerebral Circadian Rhythms

Cerebral circadian rhythms are near-24-hour oscillations generated by the brain’s circadian timing system that shape arousal, learning, memory, emotion, and other cognitive functions across the day.

Mechanisms of Interaction Between Circadian Rhythms and the Blood-Brain Barrier in Neurological Disorders

Circadian regulation of the blood-brain barrier (BBB) describes time-of-day-dependent control of the interface separating circulating blood from the central nervous system, including changes in barrier permeability, transporter activity, and neurovascular-unit function.

Time-Based Biomaterials Regulate the Brain's Circadian Rhythm

Time-based biomaterials are drug-delivery materials designed to control therapeutic exposure according to biological time rather than providing uniform release.

Endocrine Regulation of Circadian Rhythms

Endocrine regulation of circadian rhythms describes the bidirectional interaction between hormonal signals and the cellular circadian clock network that organizes physiology across the approximately 24-hour day.

Glucocorticoid Oscillatory Rhythms in Stress Environments

Glucocorticoid oscillatory rhythms describe the temporally structured secretion of cortisol in humans and corticosterone in rodents by the hypothalamic-pituitary-adrenal (HPA) axis, in which a circadian profile is constructed from recurring ultradian pulses whose amplitudes vary across the day.

Circadian Rhythms: Biological Functions, Diseases, and Therapeutic Targets

Circadian rhythms are intrinsic biological cycles of about 24 hours that organize physiology and behavior, including sleep-wake timing, hormone release, metabolism, immune activity, cardiovascular function, oxidative-stress responses, tissue repair, and autophagy.

Cortisol Arousal Response Mediates Diurnal Physiological Adaptation

The cortisol awakening response (CAR) is the rapid increase in cortisol across the first 30-45 minutes after morning awakening and represents a prominent component of the cortisol diurnal rhythm.

Bone Cell Circadian Rhythm Regulates Bone Remodeling Homeostasis

Bone cell circadian rhythm refers to intrinsic timekeeping programs operating in skeletal cells and their integration with systemic circadian signals to coordinate bone formation and resorption.

Mechanisms of Overlap and Connection Between the Circadian System and Stress Responses

Mechanistically, the SCN regulates the HPA axis and thereby produces daily rhythms of ACTH and glucocorticoid secretion, while glucocorticoids act through the glucocorticoid receptor (GR) to reset or synchronize peripheral clocks.

Cortisol Circadian Rhythm and Disease

Cortisol circadian rhythm describes the time-organized pattern of glucocorticoid secretion generated by the hypothalamic-pituitary-adrenal (HPA) axis and coordinated with the circadian clock.

Circadian Rhythm Disruption and Female Reproductive Dysfunction

Circadian rhythm disruption and female reproductive dysfunction can be framed as a failure of temporal coordination across the hypothalamic-pituitary-gonadal (HPG) axis, in which central and peripheral clocks normally organize hormone secretion, ovarian activity, implantation, and parturition.

Protein Phosphorylation and the Sleep-Wake Cycle

Protein phosphorylation has emerged as a central molecular mechanism connecting sleep-wake homeostasis with circadian timing because changes in phosphorylation can regulate protein activity, stability, localization, and molecular interactions.

Molecular Basis of Circadian and Sleep Regulation in Brain Cells

Circadian and sleep regulation in brain cells can be framed as a coupled system in which cell-autonomous molecular clocks coordinate with sleep-homeostatic signals across neurons and astrocytes.

Melanopsin Gene Variants and Circadian Rhythms

OPN4, is a blue-light-sensitive opsin photopigment expressed in intrinsically photosensitive retinal ganglion cells (ipRGCs) and participates in non-image-forming responses to environmental light, including circadian photoentrainment, pupillary light responses, and regulation of sleep.

Circadian Rhythms and Mood Disorders

Circadian rhythms are entrainable endogenous rhythms that respond to external stimuli and regulate physiological functions, with the suprachiasmatic nucleus (SCN) in the hypothalamus acting as the mammalian master clock and synchronizing tissue-specific peripheral clocks.

Endocrine System and Circadian Rhythms

Circadian rhythms are endogenously generated daily patterns of physiology and behavior, organized by an internal timing system that enables organisms to adapt to recurring environmental events such as the light-dark cycle and coordinates endocrine functions, metabolism, food intake, and sleep-wake behavior.

Circadian Rhythms, Gut Microbiota, and Metabolism

Circadian rhythms are endogenous time-keeping programs that synchronize physiology with recurring environmental cues, while the gut microbiota comprises intestinal microorganisms whose composition and function also fluctuate across the day.

Circadian Rhythms and Cardiovascular Health

Circadian rhythms are endogenous approximately 24-hour cycles that organize physiology across the day, and the cardiovascular system shows robust time-of-day variation in blood pressure, electrophysiology, heart rate, metabolism, vascular tone, coagulation, and myocardial repair.

Orexin Signaling: "Three-in-One" Switch for Diet, Anxiety, and Addiction

The same orexin network can organize adaptive food seeking, threat vigilance, and reward pursuit because all three behaviors require coordinated arousal.

Neuro-Immune Crosstalk in Hematopoiesis and Inflammation

Neuro-immune regulation of hematopoiesis describes how peripheral nerves and neural mediators control blood-cell production, retention, release, trafficking, and repair.

Epigenetics and Headache Therapy

Headache epigenetics is studied most extensively in migraine, a recurrent neurological disorder shaped by genetic susceptibility, hormonal state, environment, and neural excitability.

Biological Principles and Applications of Chrono-immunotherapy

Chrono-immunotherapy aligns immune treatment with circadian biology.

The Respiratory Cycle: A "Metronome" for Neuronal Activity

Breathing is both a life-sustaining motor program and a recurrent timing signal for the brain.

Prefrontal synaptic regulation of sleep pressure

Homeostatic sleep pressure is the drive that accumulates during wakefulness, promotes non-rapid eye movement sleep, and dissipates during sleep.

Circadian Rhythms & Cardiovascular Health

Circadian rhythms are endogenous ~24-hour timing systems that coordinate sleep-wake cycles, metabolism, endocrine signaling, and cardiovascular physiology.

Sleep Deprivation: Molecular Mechanisms and Biological Consequences

As humans, we spend nearly one-third of our lives asleep, yet the precise molecular mechanisms and functions of sleep remain incompletely understood.