If we are unconscious when we sleep, how do we wake up?

If we are unconscious when we sleep, how do we wake up?

In some ways we are not unconscious when we are asleep, we are in a state of sleep which means we can be aroused and awoken. When somebody is unconscious from another cause like being knocked out, you can't just wake them up. The thing about sleep is that, it's an orchestrated state, as far as the brain is concerned. It's a combination of the sleep promoting systems turning on and the 'wake from this' promoting systems turning off. And those 'wake from' promoting systems are associated with the internal clock. Now if something is going on, the 'wake from this' promoting systems will come on and try to switch sleep off. The reason we wake up is a good question. It's not a straight forward question to answer, but it's a combination of things. One is the pressure for sleep gradually dissipates and a lot of that pressure for sleep dissipates during deep sleep. So in the first 3 hours of the night, the pressure for sleep goes down. ‘Wake from this' carries on roughly at the same state. But the biological clock probably then comes on and says it's not time to wake up yet so it sort of lets the brain carry on the state of sleep. And, eventually the biological clock says ,well, dawn's arrived , it's time to wake up and get going. That's why we wake up.