A medical student has an irregular sleeping

pattern after a difficult exam period and usually sleeps only briefly and

poorly. He decides to adjust his daily routine and starts taking melatonin.

Melatonin, sometimes called the sleep hormone, is a hormone produced in the

pineal gland. Its production is circadian with a peak at night. The main

stimulus for melatonin degradation is light and especially its blue component.

The increase in its level is associated with the urge to sleep, helping the

body to induce a proper circadian rhythm. It is also an important antioxidant.

What are the pineal cells that produce this hormone called?