Getting up while lying in bed and suddenly feeling dizzy may be related to benign positional vertigo, or it may be caused by postural hypotension, cervical spondylosis, and so on. 1. Benign positional vertigo: when lying in bed and getting up, if the speed of getting up is too fast, resulting in a sudden change of the position of the head, which is likely to cause otoliths to fall off to the semicircular canals, then sudden dizziness will be manifested, which may be accompanied by blurred vision, nystagmus and other symptoms. 2. Postural hypotension: when lying in bed and getting up, if the speed of getting up is too fierce and fast, the blood in the whole body can not be redistributed in time and quickly, and due to the effect of gravity, more blood will gather to the lower limbs, which will easily induce postural hypotension, resulting in insufficient cerebral perfusion, which will show sudden dizziness, and may be accompanied by transient blackness before the eyes and other manifestations. 3. Cervical spondylosis: when patients with this disease sleep, if the neck is kept in an improper posture for a long time, resulting in stiffness and tension of the neck muscles. When you get up suddenly, due to the change of body position, it is likely to cause compression of local blood vessels, causing insufficient blood supply to the vertebral basilar artery, you may show a sudden dizziness. Lying in bed to get up suddenly dizziness, but also for other reasons, it is recommended to go to the hospital in a timely manner, after the cause is clear, by the doctor’s guidance for treatment.