It is true that from our childhood we have been told that sleeping for 8 hours is healthy but it is also true that every individual body has a different reaction towards their daily life you sleep for 4 hours not issue you sleep for 5 hours not issue but next morning if you're not feeling lazy Daisy and if your happy getting up from your bed that means you had enough of sleep to that much of sleep is enough it's after sleeping 7 hours also if you are not happy and feeling lazy and Daisy all the day long then sleep for more hours but if you are a busy schedule life try to figure out doing meditation and reduce your sleep time