for a healthy adult 6 hrs sleep a day is minimum requirement for sound mind n body but most go for 8 hrs sleep its all how u ve set the rhythm..of ur sleep cycle for me its always 8 hrs some suffer from excessive day time sleeping due to defective quality of sleep though he/she may have slept enough hrs apperantly cause may be obstruction in respiration during sleep snoring could be the tell-tale sign other is narco lepsy-excessive sleeping i dont think i need to talk abt. insomnia we all must have all gone through this enjoy sleeping....