Hi Soph,
When you get frightened your body produces adrenaline, the purpose of it is a flight or fight mechanism - basically it is what keeps us humans alive by giving us the abilty to move much quicker than we can do normallly or have much more strength than normal when we are in immediate danger.
Have you ever slammed on your brakes to avoid a car accident? You know the feeling of a sudden rush of adrenaline as it surges through your body with your heart pounding......then it gradually fades away but you are left feeling really shaky, you probably find it difficult to drive for some minutes after. This is how a healthy nervous system works in response to immediate danger.
When the nervous system is not healthy - perhaps because of depression, illness, medications, alcohol/drug abuse (which directly affect the nervous system), then this flight or fight reaction can happen when there is no immediate danger.
So what you get is a sudden rush of adrenaline for no reason - like you did in the middle of the night. You are not expecting it so you get frightened by the feelings. The body's response to fear (you're frightened so it wants to get you out of trouble by putting you in fight or flight mode) is to pump more adrenaline, so causing more of the unpleasant symptoms such as heart racing.
Now you feel like you are going to die, so in response to your fear your body produces more adrenaline and so the sensations of an adrenaline rush which are normally very short lived are now prolonged and you are in the panic attack from hell.
It will eventually pass as the body can only produce so much adrenaline in a short space of time but it will leave you feeling completely exhausted. I bet that is how you felt after.
The problem after having a panic attack is that you then get frightened it is going to happen again. Fear causes the body to produce adrenaline and if your nervous system is not too healthy (as I said above) then you will have an abnormal release of adrenaline putting you into fight or flight when there is no immedate danger to life. And so another panic attack begins.
This is why people who have never had panic attacks, have one and then suddenly find themselves having them all the time. They live in constant fear of the next one, so a unhealthy nervous system is now in an almost permanent cycle of fear, producing adrenaline, fear.
If you are having a panic attack you can stop the production of adrenaline and stop it in its tracks by not being frightened of it. Easier said than done but the book Self Help for Your Nerves by Dr Claire Weekes is an excellent resource in learning how to do this.
Understanding what panic attacks are and applying the methods in the book stopped my panic attacks very quickly. I was so bad that I couldn't even walk near windows in my house or go near knives in the kitchen without being gripped by fear and panic attacks.
Are you just sober a short time? If that is the case the panic attack has probably got something to do with withdrawal. Your central nervous system has some healing to do. The more it heals the less likely it is to produce adrenaline when it is not supposed to. However if you do find them happening again, I would highly recommend that book.
If you are frightened remind yourself that no-one dies of a panic attack.....but they do die from drinking.
Take care.