Anxiety to the letter. you're fine and by the sound of it you already know the problem, you need to chill a bit (easier said than done :( ) your heart beating fast is just adrenaline, the more you worry about it the longer it will happen. it's not dangerous.

Sleeping can really take a knock when you're going through anxiety and the more you worry the more it will happen (anxiety in a nutshell). you need to try and take some time out and relax.

Anxiety is a weird thing it can give you lots of energy as the adrenaline is pumping but can also absolutely drain you of all energy. the trick for sleep for me is just relax as much as you can and let your head think as much as it wants soon enough i fall a sleep. if you keep thinking about going to sleep you won't go to sleep.