What stage of sleep occurs when you get disturbed during a deep stage of sleep?

Hi everyone.

If someone is in a deep stage of sleep and something were to disturb them like a loud noise or light what stage of sleep would they switch to. If they were in stage 3 sleep and changed to another stage of sleep would that person jump back to stage 3 sleep after the noise passes or would they keep going threw the normal sleep cycle starting with the stage of sleep the noise put them in. Thank you all for your help!

I watch sleep cycles at work. I have seen the brain arouse form stage 3 due to noises and return right back to it. An arousal is a wakening of the brain for at least 3 seconds. However, if the incident woke you up...you actually got up for a bit, you would probably go through a short bout of stage 1 ( less than 3o seconds) to stage 2 for a bit and back to 3. Just depends. We spend the majority of time in stage 2. and REM doesn't necessarily follow stage three immediately, especially in the beginning of the night.