circadian rhythm
These athletes are competing in a different time zone, and will have to make a huge circadian adjustment.
There are circadian and seasonal variations in the secretion of these hormones.
Light-sensitive pigments found in cells all over the body send circadian signals to the brain.
Our internal clock runs a bit longer than 24 hours, hence its Latin name, circadian, which means "about a day."

SMART Vocabulary: related words and phrases

Days & times of day
afternoon
afternoons
all day
am
arvo
high noon
hour
in broad daylightidiom
in the dead of night/winteridiom
last orders
night
noontime
o'clock
office hours
opening time
overnight
the witching hour
twilit
workday
working day

Examples of circadian

circadian
Such parallel findings point to an intimate relationship between the neurotransmitter systems targeted by drugs and the circadian rhythms targeted by chronotherapeutics.
The diurnal rhythm of crying becomes progressively more distinct, reflecting the increasing strength of the circadian drive.
All circadian rhythms which have been studied ultimately adapt, but this may take weeks.
If their eyes are primarily circadian in function, have pathways concerned with image formation, color, and motion been discarded?
Ovulation and oviposition in birds are the best known and best characterised circadian processes controlled by light/dark signals.
Cloning and characterization of a mammalian melatonin receptor that mediates reproductive and circadian responses.
Intrinsic light responses of retinal ganglion cells projecting to the circadian system.
Circadian clocks located in the photoreceptors and retinal neurons regulate melatonin synthesis in the eye.
Phototransduction by retinal ganglion cells that set the circadian clock.
Effects of exogenous melatonin on circadian disc shedding in the albino rat retina.
However, evidence for circadian control of dopamine synthesis and release is still controversial.
Such a mechanism provides an alternative to one involving circadian control of retinal responses.
Rather, light acts indirectly by modulating the output of the circadian clock.
Limulus photoreceptors do not contain an endogenous circadian oscillator, but rely upon efferent outflow from a central clock for circadian timing.
Little is known about how circadian clocks and photoreceptors communicate to regulate shedding.
See all examples of circadian
These examples are from corpora and from sources on the web. Any opinions in the examples do not represent the opinion of the Cambridge Dictionary editors or of Cambridge University Press or its licensors.