Since you are aliasing your symbols with globs you get circular calls. *

Try code refs instead 

 my $actual_sleep = \&CORE::GLOBAL::sleep; 

# and later

 $actual_sleep->($_[0])

[download]

Untested!

update

That's the normal way to install a wrapper, but I'm not sure if that's recommended with builtins. ..

Cheers Rolf
(addicted to the Perl Programming Language :)
Wikisyntax for the Monastery

*) see demo here Re^5: Copy a builtin sub to a different name and then override

In reply to Re: Copy a builtin sub to a different name and then override by LanX
in thread Copy a builtin sub to a different name and then override by bliako

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