6 - 7 hours. I like to set my alarm at 6 and after waking up I set it again at 7 or so. I'm like Tri Girl. Or, since I live in the cold north, I may have to warm up the engine of my car, so I must wake up to plug in the warmer. Brrr! Fancy going out half asleep, your coat half open, shoes quite carelessly on, tramping through the frost: -10 - -30 grades Celsius. It's heaven to cover myself again under the warm blanket.
Sometimes I sleep less than 5 hours. If it's just one night, it is nothing to me. At weekends I take the lost hours back and sleep until 10 o'clock.