Mysteries of Sleep: Brain Activity and Sleep's Restorative Effects

Lab rats may provide us with new clues on the mechanisms that make sleep restorative. A study published Wednesday in the Journal of Neuroscience, the authors say, is the first to precisely measure brain energy to learn more about the biological functions of sleep.

Researchers observed a dramatic energy surge in certain parts of rats’ brains when the animals first fell asleep. While the rats were in deep sleep levels of adenosine triphosphate (ATP), a molecule sometimes referred to as the energy currency of life, increased in four key brain regions. Overall brain activity decreased. When researchers kept the rats awake there was no measurable energy surge.

The parts of the brain where this was observed are associated with wakefulness. One of the areas this was observed was the frontal cortex, a part of the brain associated with high-level thinking.

The authors of the study believe the flare-ups power the restorative processes only happens when during sleep. Daily waking functions may consume most of the brain’s energy, preventing restorative effects.