Waking up in terror to the slightest sound

For the last week or so I've been waking up in the night in full terror. This happens suddenly and is triggered by the most innocent sounds - like my boyfriend switching off light, closing his laptop etc.
It seems that my brain is hyper-sensitive listening to any kind of sound, and when there is even the gentlest one, I wake up TERRIFIED - with my heart racing and wide open eyes.

I know it's not related to dreams because I normally remember my dreams, and I know I have been having nightmares for a while. When I wake up from the nightmares, I am not as scared as I get when the sounds awaken me.
When I wake up scared by a sound, I feel like an extemely scared animal full of adrenaline.

Does that sound familiar? What could be causing that?
I'm desperate to find an answer as I am getting more and more drained and exhausted from this.

Thanks in advance!