what is self timer on a digital camera
Self timer A self timer is a device on a camera that gives a delay between pressing the shutter release and the shutter's firing. It is most commonly used to let photographers to take a photo of themselves (often with family), hence the name.
Circadian rhythm A circadian rhythm (/sɜːrˈkeɪdiən/) is any biological process that displays an endogenous, entrainable oscillation of about 24 hours. These 24-hour rhythms are driven by a circadian clock, and they have been widely observed in plants, animals, fungi, and cyanobacteria.[1]