if you havent been on alot today, then do it... the only way they realy can tell is if you're playing upwards of 10-15 hours in a day. so you probly sleep 8 hours, i wouldnt leave it on if you've played more tha 8 hours today. i bets its ok to leave it overnight once in a while =|
For safety i'd get another script, or don't bot at all. If you wan't to bot you need to be very careful, workout how many hours you'll be on runescape, if it exceeds 10hours then my advice is not to do it.