I think there have been studies where people in sleep labs without any natural light, clocks or other cues mostly tended toward ~25-hour days. The "disorder" p

I think there have been studies where people in sleep labs without any natural light, clocks or other cues mostly tended toward ~25-hour days. The "disorder" part is when you can't help but do this, despite having access to all those cues and despite all efforts to the contrary.