The surprising role of sleep in maintaining a balanced brain
You can go to bed frazzled, exhausted and out of sorts, have a few bizarre dreams about school, work and a backwards-talking dwarf, and then wake up feeling great. It can be a dramatic change, leaving you able to focus better as well as handle stress with less drama, and yet, we’re still not entirely why this cycle works. Dreams seem to be a side-effect of re-encoding memories, but perhaps the key to our morning rejuvenation is somehow part of how our brains self-regulate, in a process called homeostatic plasticity.
Mental moderation
Allowing for a sort of strange analogy, imagine our brains are like a car engine. Too much activity, attempting to process and be conscious of every single possible stimulus, would be like running an engine too hard. After operating at high rpm for too long, you’d burn the engine out, or in the case of our brains, reach an epileptic-like state of over-activity. One the flip side, if the brain ‘idled’ at too low an rpm, it’d more or less stall and shut down. Fortunately, it appears that it is capable of “re-balancing” itself to keep things running smoothly.
This hypothesis was tested at Brandeis University with eye-patch wearing mice. The mice had one eye covered while one eye was covered for nine days, during which time their brain activity levels were monitored continuously. The continuous observations let the researchers track how the mice’s brains initially had less activity in response to less visual stimuli, but then bounced back to their normal range. These patterns were expected, but the terabytes of data from the mice also showed something about homeostatic plasticity that wasn’t expected: when it was active.
No homeostatic night-shift
Researchers had thought that sleep was the time that our brains hit ‘reset’ for the day, re-balanced our cognitive loads and set us straight for the next morning. Instead, the mouse brains seemed stop homeostatic mechanisms when they went to sleep, only resuming them when they woke back up. In fact, the longer mice were kept awake, the more homeostatic plasticity was at work. Naturally, a batch of new questions have now popped up, including how our self-regulating mechanisms can work at the same time we’re processing new information when we’re awake? And what is it about sleep that stops homeostatic plasticity? Does the garbage collection or memory encoding require a freer rein to do their work?
It seems like someone might need to stay up late to find some answers.
Source: Sleep suppresses brain rebalancing, Scienmag
