Chronic sleep deprivation has debilitated his ability to work effectively.

debilitated 是动词 debilitate 的过去分词形式。debilitate 由前缀 de-（表示"减少、去除"）和词根 bility（来自拉丁语 habilitas，意为"能力"）组成，字面意思是"使能力减弱"，即"削弱、使虚弱"。在句中表示"已经严重削弱了"的状态。