Lying down and dizziness may be caused by benign positional vertigo, cervical spondylosis, cerebral blood supply insufficiency and other diseases. 1. Benign positional vertigo: when lying down, due to the sudden change of head position, it is likely to cause otolith dislodgement. When the otolith is dislodged to the semicircular canals, it may cause dizziness and spinning of the head, which may be accompanied by symptoms such as ocular nystagmus and rotating of vision. 2. Cervical spondylosis: especially in patients with cervical disc herniation, when lying down, it is easy for the position change to lead to the compression of local blood vessels by the protruding cervical discs, resulting in insufficient blood supply to the vertebral basilar artery, which may cause dizziness and dizziness, and may be accompanied by headache, neck and shoulder pain and other symptoms. 3. Insufficient blood supply to the brain: If there is hyperlipidemia and cerebral atherosclerosis, the blood is too viscous and the lumen of blood vessels becomes narrow, resulting in slow blood flow, which will cause insufficient blood supply to the brain. This kind of patients when lying down, due to the slow speed of blood flow in the body, will aggravate the insufficient blood supply to the brain, it may cause dizziness, the sky spinning. Lying down dizziness, if the symptoms continue to be unable to alleviate, or there are other obvious discomfort manifestations, should be timely to the regular hospital consultation, clear diagnosis of the causative factors, by the doctor’s guidance for treatment.