I am a 19 year old male, very athletic and exercise often, usually in mornings, consisting of weight lifting and cardio.
Recently, I've had this strange feeling of being lightheaded. It is not present in the morning when I wake up, when I exercise or through most of the earlier part of the day. Usually starts happening later in the day and it's only when I'm at rest. Sitting down, and even more concerning, when I go to bed at night. When I'm up and moving around, I'm fine.
I know that I have blood pressure slightly below normal and a heart rate at just 40 bpm, though I have heard that is normal for athletes.
I also feel like most places I've looked that people usually get light headed when standing up. I'm just the opposite. I have no history of heart problems, neither does my family. I'm not on any medications. I sleep right, eat right and don't do anything out of the ordinary (dont smoke or drink).
What could be causing this. Should I be concerned about my heart possibly having problems? How about my brain? This is very worrisome and I get so afraid when it's time to go to bed. Please help. Thank you very much.
-d