Anecdotally, when camping I often wake up shortly before dawn when temperatures have dropped. I imagine that poor thermal regulation and lower serotonin in the

Anecdotally, when camping I often wake up shortly before dawn when temperatures have dropped. I imagine that poor thermal regulation and lower serotonin in the early morning is partly the reason for waking up early. I wonder if this is a hold over from our early days as a species; as hunter gatherers it would be advantageous to be up and awake before it's light out.