---
name: sleep
status: documented
runtime: pp
source: src/runtime/pp/time.rs
---
```{index} single: sleep; Perl built-in (pp runtime)
```

# sleep

## Synopsis

```perl
my $slept = sleep(5);    # pause 5 seconds, returns 5
sleep;                   # sleep forever (until signal)
# with: use Time::HiRes qw(sleep);
sleep(0.5);              # fractional seconds
```

## Description

Suspends execution for the specified number of seconds.

Causes the process to sleep for the given number of whole seconds.
Returns the number of seconds actually slept, which may be less
than requested if a signal interrupted the sleep.

If `Time::HiRes::sleep` has been imported into the current package,
fractional seconds are supported and the override is used instead.
`Time::HiRes::sleep` dies on negative values.

Without arguments, sleeps indefinitely (until a signal arrives).
Negative values are clamped to 0.

Uses `libc::sleep()` (not `std::thread::sleep`) so that signals
like `SIGALRM` can interrupt the sleep.  If interrupted, any
pending `$SIG{...}` handler is dispatched synchronously before
returning.

## See also

alarm, Time::HiRes, select