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.
Light is not just for vision. It is well known that humans have a biological clock located in the suprachiasmatic nuclei that generates and regulates circadian rhythms. Biological rhythms that repeat approximately every 24 hours are called circadian rhythms.