Jupiterimages/Brand X Pictures/Getty Images. Panic is a natural reaction when you're served with a subpoena, but as far as legal documents are concerned, a subpoena duces tecum is one of the more innocuous ones you can encounter.
Circadian rhythms are biological oscillations that recur with a period of approximately one day. Health issues related to circadian rhythms include jet lag, shift work, seasonal depression, and time-of-day variations in response to medical treatments.
The term circadian comes from the Latin circa, meaning around (or approximately), and diÄs, meaning day. The formal study of biological temporal rhythms, such as daily, tidal, weekly, seasonal, and annual rhythms, is called chronobiology.