The calcium levels are regulated by the pineal gland?

The pineal gland primarily regulates the production of melatonin, a hormone that influences sleep-wake cycles. While it plays a role in various physiological processes, calcium levels in the body are mainly regulated by the parathyroid hormone, calcitonin, and vitamin D. These hormones work together to maintain calcium homeostasis in the bloodstream and bones. Therefore, the pineal gland is not directly responsible for regulating calcium levels.