REM sleep deprivation can lead to distorted perceptions, such as words appearing misspelled or hallucinating movement of objects.

“I know this from my own experience of I've ever been sleep deprived, which unfortunately happens too often because I'm terrible with deadlines, pull an all-nighter, the word the starts to look like it's spelled incorrectly. And the is a very simple word to spell, but things start to look a little distorted. And we know that if people are deprived of REM sleep for very long periods of time, they start hallucinating. They literally start seeing relationships and movement of objects that isn't happening.”