The longer the night wears on, the stranger our dreams become, according to a small, new study titled "The Effect of Time of Night on Wake–Dream Continuity." The authors found that, at the beginning of the night, our dreams have some basis in reality. Often, they reflect things we saw, did or thought about during the day. By the time we've been out for a few hours, however, things start to become more and more bizarre and detached from the real world.
As Time reports, the authors arrived at these findings after monitoring 16 sleeping people for two nights. When the research subjects drifted into a dream-filled slumber, as indicated by sensor, the team woke them up and asked them what they had been dreaming about. Each subject was woken four times each night. They also reported on what they had just been dreaming about when they got up in the morning.
Both strangeness and emotion intensified as the night wore on, the team found. There's also the possibility, though, that being jolted awake four times throughout the night might have had something to do with people's increasing departure from reality.