Impaired quality and efficiency of sleep impairs cognitive functioning in Addison's disease.

•First study investigating whether disrupted sleep might be a biological mechanism underlying memory impairment in patients with AD.•Clinically relevant sleep disruptions and declarative memory impairment in patients with AD.•No deficits in procedural memory.•A period of sleep benefits memory performance in healthy controls, whereas patients with AD derive no such benefit.•Clinicians should prioritize treatment of disrupted sleep in patients with AD.