What are the causes of Sighted Non-24?

Typically, cases of Non-24 without light perception (blindness) are due to a lack of light cues. But Sighted Non-24 is not well studied by researchers yet. These are some possible underlying causes of Sighted Non-24:

• It may be due to a neurological disorder with an abnormal functioning of the suprachiasmatic nucleus (SCN) in the hypothalamus.
• It could be due to the retina being too sensitive or not sensitive enough to light signals.
• Sometimes, Delayed Sleep Phase Syndrome can develop into Non-24. This is often due to chronotherapy. Chronotherapy is a “treatment” prescribed by patients with DSPS to try and slowly adjust their sleeping habits. Doctors ask patients to force their sleep to a cycle their circadian rhythm is not used to and this can create an elongated circadian rhythm (Non-24).
• A pituitary adenoma can cause Non-24. This is a small benign tumor that disrupts the typical flow of chemicals that control hormones, particularly those related to sleep like melatonin.
• There may also be genetic predisposition. Researchers are currently studying the genetic involvement that may be present in Sighted Non-24. Dr. Alina Patke and her associates at The Rockefeller University are among those studying how genetics are involved in circadian rhythms.
• Mycotoxins from exposure to certain molds may alter the HPA axis (hypothalamic / pituitary / adrenal axis). Mycotoxins can be tested through RealTime Labs, for example, after provoking the test 30 minutes prior with some form of sweating, like exercise or sauna.
• Some Sighted Non-24 patients are neurodivergent or are on the autism spectrum. For some, differences in neurology may play a role.
• There are likely other unknown causes. We hope raising awareness will inspire researchers to continue searching. The circadian rhythm relies on neurology, steroids, hormones, chemicals, and environmental cues. Because there are so many components to the circadian rhythm, there are many variables that may be altered enough to result in Non-24.

Because many of the underlying causes for Sighted Non-24 are neurological and involve the hypothalamus and pituitary, an MRI of the head may be an insightful option to help rule out pituitary adenomas, damage to hypothalamus, etc. These possible underlying causes are one of the reasons Sighted Non-24 patients may have better luck seeing a neurologist who specializes in sleep rather than seeing a sleep specialist (as many sleep specialists also specialize in pulmonology and may not be well-versed in the circadian rhythm).