Sighted Non-24 is not well studied by researchers yet, but we know of several causes.
It may be 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 factors at play. 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.
Some Sighted Non-24 patients are neurodivergent or are on the autism spectrum. For some, the differences in neurology may play a role.
There are likely other unknown causes. We hope raising awareness will inspire researchers to continue searching.