I think you bring up a really interesting point - and in my mind, it's where I keep feeling as if I need an explanation. I realize that college students do not keep regular schedules. However, many of them do use stimulants of various kinds (Source: q'naires given to over 2000 of my own students in the past 7 years). I am including lots of coffee, but frankly, it's often something else as well.
OTOH, Caleb is at an age where such illnesses as bipolar first begin their slow ramp-up.
And, some people just generally don't sleep much. But that's three different hypotheses (and the people who don't sleep much may be experiencing some cognitive changes as a result).
There is other research that shows that exam time is exceptionally stressful for college students. A large survey at my own college replicated the national stats: lots of anxiety and depression; 1 out of 6 of our students said they had contemplated suicide in the past 3 months. 1 out of 15 had considered a specific method of suicide. Even more students reported anxiety or panic attacks.
So I guess my initial impressions always go towards mental health and cognitive functioning of the missing person. If in fact Caleb was having trouble sleeping (for whatever reason), after putting the dog back in the apartment, what did he do next?
Some here on this thread seem to think if's useful to consider that the bridge report was accurate - others think it might be in error. There is a large body of water nearby. Statistically, the literature on missing persons indicates that for young males, bodies of water are a leading risk. Lots of other cases we've covered here have that component (or the still-missing went missing near a body of water).
Riley Strain
(MO)
Owen Klinger
(OR)
Plus that case where the frantic young man contacted his parents by phone, where first he said he was in the middle of nowhere, lost, and his GPS did place him near a river. He utters a last expletive as he apparently goes into the water.
We know that Caleb loved being near the water, we know he seems to have slept less than many of us do.
All just IMO and musings.