Hi doc.whenever i sit or lay down a period of time i always feel dizzy and a blurry vission. so may i ask what is it?

Dizzy/blurred vision: If dizzy ,when arising may be orthostatic hypotension, Body has to adjust to gravity and blood pooling in the legs when standing, and vessels contract. In some, the process is not that efficient especially if you have baseline low blood pressure, so blood pressure drops and dizzy. Get up slowly, keep hydrated (not pure water only). Rarely POTS (postural orthostatic tachycardia) Discuss w/doc