If you dilate dream time, it feels as though the dream lasts longer. Some have reported successfully accomplishing this, with effects reaching up to 2+ years. Anything longer seems absurd, but there is a guy who supposedly had a dream that lasted 100 years.

Dream time dilation isn't proven, but it isn't researched very thoroughly, either. Researching time dilation is one of my current goals.


Without using time dilation techniques to alter subjective time, dream time passes generally at the same speed as real time, as others have explained. LaBerge did prove this through REM eye movements. That isn't the question anymore; whether or not dream time can pass more slowly or quickly is the question. Nobody has done definitive research proving this either way, and the large majority of evidence is anecdotal with little proof to back it up.

Even so, we can't count active time dilation as an impossibility. It just hasn't been researched enough.