Non-24: More Than Just a Sleep Issue

Non-24-Hour Disorder (Non-24), also known as “free-running type,” is a serious chronic circadian rhythm disorder (CRD).^1,2 CRDs represent about 10% of the approximately 75 clinical sleep disorders that are formally recognized.³

While abnormal timing of hormonal patterns can confirm the presence of a CRD, patients complain about the consequential circadian rhythm sleep disorder; disturbed sleep being the most commonly reported symptom associated with misaligned circadian rhythms.⁴

Non-24 occurs primarily in people who are totally blind because they lack the light perception necessary to entrain, or synchronize, the master body clock in the brain with the 24-hour day-night cycle. For these people, the day-night cycle shifts in and out of alignment with the 24-hour social day.^1,2,5

In addition to sleep-wake issues, people who are totally blind with Non-24 often experience symptoms in other physiologic systems governed by the circadian system such as cognitive function, mood, and metabolism. These symptoms can occur even in the absence of sleep complaints.¹

Learn more about the physiology of Non-24 here.