# This is from memory and almost certainly contains bugs
use Time::Local;

$now = time;
@now_array = localtime($now);

# 1:00am is tomorrow if it is after that today
if($now_array[2] >= 1)
  {
    $now_array[3]++;
  }

# Set 1:00am in the structure
$now_array[2] = 1;
$now_array[1] = 0;

# Convert to seconds
$then = timelocal(@now_array);

# Now wait
sleep($then - $now);