For a healthy person in a good bed without interruptions, 8 hours. But if you have trouble falling back to sleep after being woken up, you can lose a fair amoun

For a healthy person in a good bed without interruptions, 8 hours. But if you have trouble falling back to sleep after being woken up, you can lose a fair amount in a noisy environment. If your bed is bad, you may wake up or not fall into a deep sleep. And there are medical conditions that can make you be unconscious but not actually sleeping. Plus, high stress levels interferes with sleep.