My wife’s last days provided many profound truths for me. Many I had not considered or experienced. One stands out more than most. It is that when the threat of death is near, humans (and likely other species) start to move. Sleep becomes a transitory state between states of movement and responses to perceived threats. When near death, humans do not sleep at night and tend to sleep during the day. The workers at the hospice confirmed this perception. They find it difficult to regulate sleep in the customary pattern of night sleep and day time activity. Instead, they find that the pattern is reversed; night time movement and a sense of threat, with day time sleep. It was this pattern of behavior in Bonnie that destroyed my sleep. It was worth it to keep her safe, but I have wondered about the pattern.
It is not hard to see from an evolutionary perspective. The daytime was the human evolutionary niche. Our sweat glands, upright stature, hairless bodies and sophisticated thermoregulatory systems made the peak temperature, day time hours our niche. No other animal, at least among predators, was able to tolerate the temperatures humans could endure and work at. We ruled the day at peak temperatures in a way no other animal could.
But, we were at risk in the night when lower temperatures gave predators their time to hunt and kill. That is why humans sleep during the night—to be less of a target to predators. The night was the most dangerous time for ancestors and we show it in our behaviors even now. This is the time when we experience our deepest fears. We seldom experience these fears in the depth they are felt during the night, the time of our most profound risk.
This pattern is especially prominent in children. But, alas, it was also evident in my dear wife’s fears near the end of her life, when her reasoning had been damaged by the vasculitis. As shall be the fate of all of us: when near death, neural programs revert to their evolutionary default settings.