"A circadian rhythm, or circadian cycle, is a natural oscillation that repeats roughly every 24 hours."
Study of natural cycles in living organisms.
Circadian rhythms: These are the biological processes that occur in a 24-hour cycle, including sleep patterns, hormonal regulation, and other physiological processes.
Ultradian rhythms: These are biological processes that occur in shorter cycles than 24 hours, such as hunger and thirst, the menstrual cycle, or the sleep cycle.
Infradian rhythms: These are biological processes that occur in longer cycles than 24 hours, such as reproductive cycles, seasonal changes, or long-term hormonal cycles.
Entrainment and synchrony: These are the mechanisms by which biological rhythms adjust to external cues, such as light, temperature, or social cues.
Endogenous rhythms: These are the biological rhythms that are generated internally, without any external input or cue, and are often associated with specific genes or biochemical pathways.
Zeitgebers: These are external cues that help entrain and synchronize biological rhythms, such as sunlight, temperature, or social cues.
Chronotypes: These are individual differences in the timing of biological rhythms, such as the tendency to be a morning person or a night owl.
Sleep and wakefulness: These are the most well-known biological rhythms, and are regulated by the circadian and ultradian cycles.
Melatonin: This hormone, produced by the pineal gland, plays a key role in regulating the circadian rhythm by promoting sleepiness at night and wakefulness during the day.
Jet lag and shift work: These are disruptions to the circadian rhythm that can occur when traveling across time zones or working irregular hours, and can have various negative health effects.
Seasonal affective disorder: This is a type of depression that is associated with the seasonal changes in light exposure, and is thought to be related to disruptions in circadian rhythms.
Biological clocks: These are the systems within cells and organisms that regulate biological rhythms, and are often based on feedback mechanisms involving gene expression and protein synthesis.
Chronotherapy: This is a type of treatment that aims to adjust the timing of medication or other therapies to better align with an individual's circadian rhythm, in order to optimize effectiveness and minimize side effects.
Aging and biological rhythms: As we age, our biological rhythms may become less robust and more prone to disruption, which can contribute to various health problems.
Evolution of biological rhythms: Biological rhythms have evolved in many different species over time, and are thought to be adaptive responses to various environmental cues and challenges.
Circadian rhythms: Rhythms that repeat approximately every 24 hours, and are synchronized to the day/night cycle.
Ultradian rhythms: Rhythms that occur repeatedly within a 24-hour cycle, lasting less than 24 hours.
Infradian rhythms: Rhythms that span a period longer than 24 hours, occurring less than once per day.
Diurnal rhythms: A type of circadian rhythm that is active during the daytime and inactive at night.
Nocturnal rhythms: A type of circadian rhythm that is active at night and inactive during the day.
Seasonal rhythms: Rhythms that occur as a result of the changes in the seasons, which affects biological processes and cycles.
Lunar rhythms: Rhythms that are synchronized to the phases of the moon, particularly the full moon.
Tidal rhythms: Rhythms that occur as a result of the ebb and flow of the tides.
Endogenous rhythms: Rhythms that are generated internally, without any external cues or inputs. These rhythms are governed by an internal biological clock or pacemaker, and can persist even in the absence of environmental cues.
Exogenous rhythms: Rhythms that are triggered by external cues or inputs, such as light, temperature changes, food availability, or social cues.
Homeostatic rhythms: Rhythms that help maintain and regulate the internal physiological balance or homeostasis. These rhythms are involved in processes such as sleep, hunger, thirst, and body temperature regulation.
Metabolic rhythms: Rhythms that are involved in the regulation of metabolic processes, including energy expenditure, digestion and absorption of nutrients, and the breakdown and synthesis of molecules.
Reproductive rhythms: Rhythms that are involved in the regulation of reproductive processes, including menstrual cycles, ovulation, and fetal development. These rhythms are particularly important for the timing of reproduction and fertility.
"Circadian rhythms can refer to any process that originates within an organism (i.e., endogenous) and responds to the environment (is entrained by the environment)."
"[...] the primary function is to rhythmically co-ordinate biological processes so they occur at the correct time to maximize the fitness of an individual."
"Circadian rhythms have been widely observed in animals, plants, fungi and cyanobacteria."
"There is evidence that they evolved independently in each of these kingdoms of life."
"The term circadian comes from the Latin circa, meaning 'approximately', and dies, meaning 'day'."
"Processes with 24-hour cycles are more generally called diurnal rhythms."
"Diurnal rhythms should not be called circadian rhythms unless they can be confirmed as endogenous and not environmental."
"Circadian rhythms are adjusted to the local environment by external cues called zeitgebers, which include light, temperature and redox cycles."
"[...] external cues called zeitgebers (from German Zeitgeber), which include light, temperature, and redox cycles."
"In clinical settings, an abnormal circadian rhythm in humans is known as a circadian rhythm sleep disorder."
"Circadian rhythms can refer to any process that originates within an organism (i.e., endogenous) and responds to the environment (is entrained by the environment)."
"The primary function is to rhythmically co-ordinate biological processes so they occur at the correct time to maximize the fitness of an individual."
"Zeitgebers (from German Zeitgeber) include light, temperature and redox cycles."
"Circadian rhythms have been widely observed in animals, plants, fungi and cyanobacteria."
"Diurnal rhythms should not be called circadian rhythms unless they can be confirmed as endogenous and not environmental."
"Their primary function is to rhythmically co-ordinate biological processes so they occur at the correct time to maximize the fitness of an individual."
"A circadian rhythm, or circadian cycle, is a natural oscillation that repeats roughly every 24 hours."
"They are adjusted to the local environment by external cues called zeitgebers, which include light, temperature, and redox cycles."
"Circadian rhythms are regulated by a circadian clock whose primary function is to rhythmically co-ordinate biological processes so they occur at the correct time to maximize the fitness of an individual."