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Purpose of Review. Obstructive sleep apnea and chronic insomnia are the most common sleep disorders in adults. Both sleep disorders can adversely affect physical and mental well-being. Cognitive function has been extensively studied in relation to chronic insomnia and obstructive sleep apnea. This paper reviews the recent studies investigating the cognitive effects of insomnia and obstructive sleep apnea as well as the potential benefits of treatment.

Recent Findings. Recent studies indicate that insomnia is associated with impairments in attention, memory, and executive function.  Chronic insomnia may have a moderating role in mild cognitive impairment and Alzheimer’s dementia. Mood and anxiety disorders may moderate the effects of insomnia on cognitive function. Hyperarousal and short sleep time associated with insomnia are risk factors for cognitive impairment. Cognitive behavior therapy for insomnia may improve cognitive function but more studies are needed. Nonbenzodiazepine receptor agonists improve insomnia without causing cognitive impairment.  Benzodiazepine use is associated with cognitive impairment.

Obstructive sleep apnea is associated with impairments in attention, concentration, memory, and executive function with apnea severity as measured by the apnea hypopnea index and severity of nocturnal hypoxemia being the largest risk factors.  Untreated obstructive sleep apnea may have a significant impact on the progression of mild cognitive impairment and Alzheimer’s dementia.  The impact of obstructive sleep apnea treatment, particularly with continuous positive airway pressure, appears to mitigate and slow the rate of cognitive decline but more randomized controlled studies are needed. 

Summary. Standardized cognitive assessments and larger, long-term controlled prospective studies with diverse populations are needed to further elucidate the cognitive impairments associated with chronic insomnia and obstructive sleep apnea. More studies are needed on the benefits of various treatments for obstructive sleep apnea and insomnia.