What are some causes of intense dizzy spells?

There is only one that I know of, tight neck muscles. When tight the muscles restrict the blood flow to the head so less new blood is getting to the brain. Less new blood drops the oxygen level and the three stages of lowered oxygen levels in the brain are; feeling very tired; getting dizzy or light headed; and passing out. When you sit up in the morning you are pulling your back and neck muscles tighter to cause even less blood to the head. This usually happens any time when standing as well. When drying your hair you have your back muscles holding the dryer up and well as tighten up neck muscles at that time to cause the same problem. To get rid of the spells you have to free up your neck muscles so the blood flow isn't restricted and here's how to free them up: Neck Release: Place your hands behind your head touching your fingers. Press into the back of your neck with them and hold the pressure on them. After 45 seconds slowly lower your head until your neck is fully extended. Release the pressure but hold your head there for another 30 seconds. For best results relax your body first by taking a deep breath and exhaling then remain this relaxed.