My first bout with anxiety started when I got engaged. Heart palpitations, had to wear a Holter monitor for a week, the works, but everything checked out fine... Skip a few years and then decided to buy my first house. I'd been staying up for tons of hours trying to bank a bunch of cash for the down payment. Was working on a project that was make-or-break for a local startup, the guy before me didn't care enough, but I wouldn't let it fail, stayed up for 4 days building it and BOOM, crippling anxiety again. Different though, couldn't take full breaths of air this time. But in both cases I wasn't getting enough sleep. Got some sleep, talked to my doctor, then my dad, and then I was fine. Used to stay up for 2-3 days during college all the time so I really didn't think much of it. Sleep is huge.