Our brain activity most closely resembles our activity during waking hours because of course this is where our dreams occur. A study conducted at Harvard Medical School proposed that REM sleep and dreaming can be viewed as almost like a virtual reality that's been created by our brain. In other words, we sense, we act and we feel what we are dreaming. The rapid movement of our eyes which is now used to identify when someone is dreaming,. It used to confuse people because they used to think back in the day, back in even as early and recent as the 1900s that when people were dreaming they were actually partially seeing our dreams on the back of our eyelids.