In perldoc sleep, we read the following caveats:

May be interrupted if the process receives a signal such as "SIGALRM".

                   eval {
                       local $SIG{ALARM} = sub { die "Alarm!\n" };
                       sleep;
                   };
                   die $@ unless $@ eq "Alarm!\n";
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You probably cannot mix "alarm" and "sleep" calls, because "sleep" is often implemented using "alarm."

Methinks that some or all of the foregoing will prove to have exceptional relevance to your present problem.   ...

In fact, I would wager that it consists of what has been described here:   “sleeps can be interrupted by a signal, and ‘un-caught signals’ generally mean ... (oopsie! hateitwhenthishappens!!) ... Death.”

However, not to be “snarky,” tell us more!   When your script runs into trouble, what does it do?   What does it log?   The more specific detail you can give, the more specifically we can help you ... and, after all, that’s why we’re all here.