Script running in the background

Good afternoon, dear forum users! I have a question, here is the code:

while (!file_exists('./stop_script.txt')) {
    while (!file_exists('./work.txt')) {
    ,      (  work.txt )

And immediately the actual question:
Line : sleep(5);
sleep – as I understand it, stops the script “falls into sleep” for a given number of seconds (now for 5), and after this time the script continues to work.
My question might be a little silly, but it’s better to ask and blush a little than to make a mistake later.
If the sleep() function puts the script to sleep for 60 seconds – 1 minute, then during this time whether the system resources will be used, or most of the resources will be freed and will be used after the end of the “sleep”.
I’d better formulate the question differently, if I run 10 scripts almost simultaneously, where sleep will stop their work for 1 minute, will my computer “get up” or will everything be fine as it was before running these scripts?

Answer 1, authority 100%

During “sleep” only memory is wasted, almost no CPU.

The computer may freeze due to the script, but not because of sleep.