The most common cause of uncontrolled frowning during sleep is the following: 1. The most common cause is abnormal brain cell discharge, usually in the nigrostriatal cortex of the brain, abnormal activity of neuronal impulses, most often due to a past history of epilepsy, and abnormal impulses and discharges in the nuclei of brain cells. 2. Patients with previous history of stroke or acute cerebrovascular disease are prone to transient cerebrovascular ischemic attacks during sleep, especially in patients with atherosclerotic plaques in the cerebral arteries, which can cause uncontrolled frowning or nervousness during sleep.