Hi. Thanks for your query, albeit short and specific. Noted the history and understood your concerns. Getting severe dizziness on turning head in sleep, laying down, sitting up for about 5 seconds followed by getting alright can be mostly due to the following reasons: It may be that it is taking a few seconds for the fluid in the semicircular canals to get settled and well balanced hence this momentary dizziness. Another reason can be cervical spondilitis causing narrowing of the vertebral artery and thus causing momentary vertigo. I would advise you the following in such a situation: Slow rising or sleeping, avoid sudden movements of the head above the shoulder. Take an opinion of an ENT Surgeon or a Neurologist to get the proper clinical evaluation, examination and MRI/CT of the brain and the semicircular canals to know the cause and get treated accordingly.