another 12 hour night..

i know why i have to lie on the bed for 12 hours consecutively oredi.. cos i spend like 1 minute for every 15 mins sleep coughing.. so for every 12 hours i need to wake up 48 times.. which is 48 minutes.. and hence i effectively only sleep 11 hours 12 mins.. but hmm... 11 hours 12 mins is relli long ah.. but why do i still feel so tired..