For the past one and half year, I have taking about 500 mg of caffiene and 300 mg modafinil over the course of 16 or so hours. I am a young single mother and my job requires me to work very long hours. I am curious if this is having any permanent negative effect on my health, and my family has no history of heart problems. The only other medication I take is seroquel to help me sleep and occasionally a xanax when things get too stressful. I would ask doctor but I do not have insurance and these medications are not prescribed to me.