A 28-year-old woman was evaluated for 4 months of excessive daytime sleepiness (EDS), after an overnight polysomnogram (PSG) revealed neither sleep disordered breathing nor a sleep related movement disorder. A full sleep evaluation revealed the presence of heavy daytime napping and pervasive fatigue. Epworth Sleepiness Scale (ESS) Score was 10/24. No features characteristic for depression or narcolepsy were present. Chronic pain in the low back and thighs, as well as chronic daily headaches were identified as potential sleep-disrupting forces.
Risk factors for hypovitaminosis D [deficiency] included limited natural sun exposure, dark skin tone, and obesity. A 25-hydroxyvitamin D level was low, at 5.9 ng/mL.
Vitamin D supplementation was initiated at a dose of 50,000 IU once weekly, and excessive daytime sleepiness improved within 2 weeks.
One week later, a PSG with next-day multiple sleep latency testing (MSLT) failed to show significant pathology.
At follow-up, she reported resolution of thigh pain and headaches, with a significant improvement in her low back pain syndrome. EDS had resolved, and her ESS score was 1/24.
Follow-up 25-hydroxyvitamin D level was normal at 39 ng/mL. Mechanisms for her clinical improvement could include:
• Enhanced sleep quality due to resolution of hypovitaminisos D-associated noninflammatory myopathy,
• Or a possible immunomodulatory effect of vitamin D decreasing central nervous system (CNS) homeostatic sleep pressure via its effects on tumor necrosis factor-alpha (TNF-alpha) and/or prostaglandin D2.
More research is needed to determine if patients presenting with excessive daytime sleepiness should be more broadly screened for vitamin D deficiency.
Source: Journal of Clinical Sleep Medicine, Dec 15, 2010; 6(6):605-608. PMID: 21206551, by McCarty DE. Sleep Medicine Program, Department of Neurology, Louisiana State University Health Sciences Center, Shreveport, Louisiana, USA.