Hello Thus could be due to postural hypotension, low blood sugar or diabetes Thus can be related to medicines or poor functioning of heart If you can provide me more information I will be able to guide you better Any history of chest pain Do you smoke or consume liquid? You should immediately consult a cardiologist for examination, checking of blood pressure and a battery of tests like EKG Echocardiography and pulmonary function test Please take extra care while standing up, you may fall and sustain any injury Don t stay alone Hope this answers your question please feel free to ask for more assistance I will be happy to help you Wish you good health and vitality Regards