I usually tend to sleep at evening 7 o clock or 8 o clock my body tend to automatically get tired after evening or after dinner. My maximum wake up at night 9 o clock. What kind of problem is this. postural orthostatic tachycardia syndrome ?? Suddenly when I sit on chair my heart racing too much. If I fall on bed automatically my heart racing too much if I sudden stand from chair heart racing too much i thought all are belongs to anxiety symptoms, heavy sweating, dry skin no water content in my skin. . But none of the anxiety medicine helps sir.