Whenever i stand up i have a minute where i'm really dizzy and i have to stop and stand still for it to leave. i can't see properly and my head feels light. this is usually on a hot day, though i always drink lots of water, i always have a drink bottle. c

Syncope: What you are describing sounds like syncope, also called fainting. It occurs when your blood pressure is unable to increase or change enough when you change position. It is most often caused by dehydration, although if you have any chest pain, shortness of breath or a 'fluttering' sensation in your chest with the symptoms you should discuss with your family doctor. Stay hydrated when it's hot.