circadian

[sur-key-dee-uhn]

adjective

Physiology.

1. of or relating to a biorhythm or regular biological cycle occurring once every 24 hours, such as waking and sleeping.

   Exposure to blue light at night can disrupt your circadian rhythm, making your biological clock think it's earlier in the day rather than time for bed.

   He is doing research related to the circadian cycling of hormones.

circadian

/ sɜːˈkeɪdɪən /

adjective

1. of or relating to biological processes that occur regularly at about 24-hour intervals, even in the absence of periodicity in the environment See also biological clock

Word History and Origins

Origin of circadian¹

First recorded in 1955–60; from circā “about” + Latin di(ēs) “day” + -an ( def. ); circa ( def. )

Word History and Origins

Origin of circadian¹

C20: from Latin circa about + diēs day

Example Sentences

Late night TV, which once had to be watched, well, late at night — it had a sort of circadian component — has been atomized into clips to watch when you like.

From Los Angeles Times

Sleep is controlled through an internal process known as the circadian system that repeats roughly every 24 hours.

From BBC

“When the bioenergetics are damaged, you can imagine that it has detrimental effects … impacting your immune system and circadian rhythm.”

From Salon

Alcohol also affects circadian rhythms — the 24-hour body clock that responds to environmental light cues in order to synchronize our sleep-wake cycle.

From Salon

I built my day around my nights, transfixed by a false sense of control over my circadian rhythm.

From Los Angeles Times

Related Words

• constantly 
• day-to-day 
• everyday 
• often 
• periodic 
• regular 
• regularly 
• routine