Dizziness in the lying position is common in benign paroxysmal positional vertigo, as well as insufficient cerebral blood supply, hypertension or hypotension. 1. Benign paroxysmal positional vertigo: also called otolithiasis. Typical manifestation is vertigo when changing head position suddenly, which may be accompanied by nausea, vomiting, nystagmus and so on. It is prone to recurrent attacks. Otolithiasis can be treated by manipulation and repositioning. After treatment, it is necessary to avoid strenuous exercise to prevent recurrence of otolithiasis. 2. Transient ischemic attack: due to cerebral vascular sclerosis, embolism, compression and other vascular lesions, resulting in incomplete blood supply of the internal carotid artery system and insufficient blood supply of the vertebral basilar artery, transient ischemic attack will be caused by sudden change of position, which will result in lying down without dizziness, and side-lying dizziness will occur. 3. Hypertension or low blood pressure: patients with hypertension or low blood pressure can have the above symptoms when they suddenly change their body position, which can intensify the fluctuation of blood pressure and lead to dizziness or intensify the original dizziness. Lying down without dizziness side lying dizziness may also be caused by other reasons, it is recommended that patients actively seek medical attention to clarify the cause of the disease, targeted treatment.