Sleep timer on OS X

gistfile1.txt

property default_minutes : 30
property wait_percent : 50 -- wait before starting fade

set question to "Set a sleep timer for how many minutes?"
set options to {"Don't sleep after", "Sleep after", "Cancel"}

display dialog question default answer default_minutes ¬
    buttons options default button 1 giving up after 30
set {_button, _answer} to {button returned, text returned} of result

if _button = "Cancel" then return

set sleep_after to false
if _button = "Sleep after" then set sleep_after to true

try
    set sleep_seconds to _answer * 60
on error
    beep
    display dialog ¬
        "TIMER NOT RUNNING. You didn't enter a number." with icon stop ¬
        buttons {"Quit"} default button 1
    return
end try

set steps to 60
set wait_before_fading to (sleep_seconds * (wait_percent / 100))
set fade_time_step to ((sleep_seconds - wait_before_fading) / steps)

delay wait_before_fading

tell application "iTunes"
    set init_volume to sound volume
    repeat with i from 0 to steps
        set sound volume to (init_volume - (i * init_volume / steps))
        delay fade_time_step
    end repeat
    pause
    set sound volume to init_volume
end tell

if sleep_after then tell application "Finder" to sleep