Hi Actualy,
According to Gurmat :
6 hours is a man's sleep
7 hours woman's
8 hours is a child's sleep
9 hours Fool's sleep (Though i also sometime sleep 9 hours when tired)
But attaining this is a bit difficult, but i think we should. (some may disaaprove)
And another thing in reagrds to woking up i think you should fix a time such that ..after doing Nitname u should instead of sleeping..get ready and leave for your work. Coz if u woke up onc and then go sleep again and again woke up ...u will realy feel tired..
If you think it takes 3 hours to do nitname...Woke up at 3-30 am do ishnaan and start doing nitname at 4 and you will be free at 7 ...get ready take breakfast ..and set for work...
and if someone suggests better follow that.. :-)