Did You Get a Good Night’s Rest? Your Brain Didn’t

We’ve all been told at one time or another, “Turn off your brain and go to sleep.” Well, new research out of Stanford University makes it clear that, while you might go to sleep, your brain never really “turns off.”

Your brain is constantly active

Your brain may make up only 2 percent of your body weight, but it uses 20 percent of your energy. Why does your brain demand such a disproportionate amount of energy? Unlike the body, which doesn’t require as much energy when it’s resting as when it’s active, the brain uses plenty of energy all the time, whether you’re thinking hard, daydreaming or asleep. It has often seemed to scientists that much of that energy was spent on what they called useless “noise,” or irrelevant, patternless electrical activity.

Separate areas of the brain working together

The new Stanford study, led by Josef Parvizi, MD, PhD, sheds new light on our understanding of the brain’s constant activity, which, it turns out, is much more organized than previously believed. The researchers found that separate areas of the brain that work together during times of memory recall continue to work together even while people are sleeping. Other studies have indicated this all-night relationship between coordinated brain areas before, but this study, published April 8 in Neuron, is the first to confirm those other studies’ observations.

Matching activity patterns

Parvizi and his associates studied three patients who were undergoing brain monitoring as part of their epilepsy treatment. The researchers used the same intracranial electrodes that were being used for the patients’ medical procedure to learn more about the activity, both day and night, in their brains. First, the scientists observed how two separate areas of the brain, the angular gyrus and the posterior cingulate cortex, both showed electrical activity when study subjects were asked to recall information about personal memories. Then, as the same patients were resting or asleep, the researchers observed the same patterns of activity between those areas of the brain. The activity patterns were slower during times of sleep, but they were still a match to those seen when the patients were awake.

The researchers concluded that the same simultaneous activity in these regions that takes place when the brain is asked to do a specific task, such as recalling what was eaten for lunch, continues to occur spontaneously in periods of rest and sleep.

So why exactly is your brain so busy all night long? Researchers still aren’t certain why the brain continues to use energy in this way, even when you’re sleeping, but Parvizi hypothesizes that perhaps it is how that the brain continually maintains the relationship between coordinated regions.