I haven't slept for 36 hours, approaching 48 tonight.. i go work as normal during day and have energy - why can't i sleep? using no meds.

Danger zone: If you have not slept in over 36 hours, you're in the danger zone for making serious errors in judgment or driving, etc. The results can be as serious as if you're drunk. Have you been using any recreational stimulants? Do you have any family history of psychiatric illnesses, like bipolar disorder? I strongly suggest you see your physician asap for an evaluation. This can be how mania starts.

Anxiety and mood: Changes. You need to see your doctor quickly so as to prevent serious consequences from sleep deprivation. The fact that you go to work and have energy, yet have mood changes, means to me that you are going to need a full psychiatric eval to rule out not only generalized anxiety disorder, but, of even greater concern, bipolar disorder. The first thing to do, however, is to treat the insomnia.