PER2 and functioning pituitary gland adenoma: Pituitary tumours can also cause a long-term disruption of the sleep-wake rhythms of patients by compressing the optic chiasm, which can also disrupt melatonin rhythms.65, 66, 67 In the same time window, namely in samples collected between 9:00 AM and 12:00 PM, both growth hormone-secreting pituitary adenoma (GHPA) and prolactin-secreting pituitary adenoma (PRLPA) exhibited upregulated PER2 expression, compared to autopsy specimens from deceased individuals.68