Endocrine Abstracts

Suprasellar tumors that compress the optic chiasm can lead to disturbances in sleep-wake rhythms, possibly due to damage to the brain’s biological clock, the suprachiasmatic nucleus (SCN). Studies have shown that pituitary tumors with suprasellar extension impair circadian regulation and thermoregulation. In patients with a history of optic chiasm compression, there is reduced expression of arginine vasopressin (AVP) in the SCN, while vasoactive intestinal peptide (VIP) levels remain unchanged. This suggests selective impairment of the SCN, which may contribute to sleep disturbances. Additionally, patients with a history of chiasm compression show altered skin temperature regulation. Specifically, these patients exhibit lower proximal skin temperature and an absent association between pre-sleep skin temperature gradient and sleep onset latency, indicating disrupted hypothalamic control of both vigilance and thermoregulation. Furthermore, patients with hypopituitarism and optic chiasm compression demonstrate impaired photosensitive retinal ganglion cell (ipRGC) function, as evidenced by a weaker post-illumination pupil response (PIPR) compared to those without chiasm compression. This diminished PIPR is associated with delayed sleep timing but no significant differences in sleep duration or quality. Taken together, these findings support the hypothesis that damage to the hypothalamus, particularly the SCN and associated nuclei, impairs both circadian rhythms and thermoregulatory functions, contributing to sleep disturbances in patients with pituitary tumors compressing the optic chiasm.