1043 A Rare Case of Non-24-hour Sleep-Wake Rhythm Disorder in A Sighted Patient

Abstract

Abstract Introduction Non-24-hour sleep-wake disorder is a circadian rhythm sleep disorder which causes failure of endogenous circadian rhythm cycles to synchronize to a 24-hour day. Despite an unknown prevalence in sighted people, it's thought to be rare. We present a case of a sighted patient with concurrent bipolar disorder who presented with excessive sleepiness since preadolescence, and was later found to have N24SWD. Report of case(s) A 29 year old woman with bipolar disorder presented with excessive daytime sleepiness and irregular sleep schedule since age 12. During her teenage years she often fell asleep at school, and she felt the sleepiness could be associated with psychotropic medication. As she grew up, despite her bipolar disorder was well-controlled, the daytime sleepiness persisted, which caused great challenge concentrating at work and difficulty holding a job. She denies cataplexy, hypnagogic hallucinations, sleep paralysis, or restless legs syndrome symptoms. She had no history of shift work or abnormal movements during sleep. Her bedtime advanced and cycled through a 24-hour period according to sleep diary. Her rise time maintains a consistent interval with her bedtime. Previously she had multiple sleep latency test and polysomnogram, after which she was diagnosed with idiopathic hypersomnia. She was treated with several stimulants without much improvement. She was offered CBT-I but hasn’t gone. She failed trial of a standardized schedule and found it stressful. She tried melatonin and light therapy for a short time without much of success, she was subsequently started on tasimelteon and the clinical response is to be followed. Conclusion N24SWD is reportedly rare in the sighted population, with a possible different mechanism from that of the blind population. Behavioral and environmental factors might contribute to the dysynchrony between a normal central circadian pacemaker and a non-24-hour sleep-wake behavioral pattern. Our patient's sleepiness persisted despite her psychiatric disorders were in remission. Altered circadian rhythms are not uncommon in patients with psychiatric disorders, and circadian rhythm dysfunction may be a trait marker of bipolar disease. Some antidepressant are also found to cause potential iatrogenic circadian rhythm sleep disorders. Psychosocial interventions that target stabilizing daily rhythms in patients with concurrent psychiatric illness can be helpful. Support (if any)