Can’t sleep? Lots of people have that problem. Doctors speculate that the accidental overdose death of actor Heath Ledger happened because he was taking medication for a bad case of insomnia. Live near an airport or highway? Traffic noise you’re not consciously aware of can keep you awake. Kept up by a barking dog? You may not be able to stop him but you MAY be able to understand him: researchers think they have finally deciphered the language of dog barks.