But the key issue is this, that normally when we close our eyes also, we're going to sleep. You're not worried about what's going on in the world anymore. Here, you're maintaining resting alertness. So, you're focusing but you're turning inward. That's an unusual state. Normally we close our eyes periodically, we have to, but when you close your eyes for some period of time, it's normally to go to sleep and you're not worried about detecting risk or threat.