It is one of my favorite things to do, of course, and the topic of 3 stories in the 5/28/16 edition of Science News. The first is somewhat interesting, in that some research found that certain ion concentrations were involved in sleeping-waking. This is contrary to orthodoxy that key neurological systems, e.g., the RAS or reticular activating system, control the change in states. Basically when potassium ions rise in concentration in the brain and potassium and calcium concentrations fall, the brain awakens, and when potassium falls, and potassium and calcium rise, the brain sleeps. It appears, then, that the neurological systems work by modulating ionic concentrations. Anesthesia appears to work the same way. So when we are slow to awaken or to drift off, the concentrations are not properly adjusted. After reading this I thought about awakening but having difficulty getting up and going or feeling sleepy but still awake as the concentrations are being adjusted. And what about the delicious feeling of waking up and experiencing what I think is called a body yawn when your body stretches out and tenses before relaxing? Does the feedback from the body help the brain to coax the concentrations towards the awake mode? Bet so.
The second report finds that the mammalian sleep pattern of deep sleep and REM sleep is actually present in lizards. Who knew? The implication here is that 2 stage sleep appeared much earlier in evolution than previously thought, say around 300 million years ago, and that changes what we might consider as the reason we have the 2 stages because lizards do not have the memory capabilities of mammals, so what are they consolidating? And lizards can doze with some awareness a long time, so what does REM do for them that dozing doesn’t?
The third story is quite interesting because sleep researchers have found that the first night we sleep in unfamiliar surroundings, the left hemisphere remains vigilant at least through the early stages of sleep and that this seems to be why the first night’s sleep when away from home is usually not so good. They did not study this pattern over the entire night so they are not sure if the left side stays on guard the entire night or if the right side might pick up some sentry duty itself. My question is, Why the left? The right side is more concerned with the immediate situation while the left focuses more on displaced information. Is the left worrying more, so that the guard duty is more a manifestation of rumination than of vigilance? That is my bet, though why the left side becomes more ruminative away from home only on the first night is still a puzzle—the studies are not systematic in exploring these issues. The article also mentions the folk belief, true to me, that parents can sleep through thunderstorms but awaken when their infant chirps. I will bet this is a more right sided phenomenon than left but I can find no studies on this. Come on, graduate students, here is a good study for that paper you must do.
After a cat nap, you know, just a short ionic fluctuation of the lizard brain and letting the hippocampus consolidate memories of my recent experience, I will travel on.