Non-24-Hour Sleep-Wake Rhythm Disorder in People with and without Sight

Non-24-hour sleep-wake rhythm disorder (N24SWD) is more common in totally blind individuals.

• N24SWD is characterized by an inability to adhere to a 24-hour sleep schedule.
• Individuals with N24SWD exhibit sleep-wake cycles that deviate from 24 hours, especially in the absence of a light-dark cycle.
• It is relatively rare in sighted individuals but may be linked to other sleep or psychiatric disorders.
• The disorder is associated with a disruption in the circadian pacemaker in the hypothalamus due to insufficient light information.

Simplified