03/12/2026
The brain remains highly organized and active during sleep. Using advanced imaging combining EEG, PET, and MRI, researchers studied how brain activity and energy use change as people transition from wakefulness into non-REM sleep. They found that as we fall asleep, the brain’s overall energy use declines, while large rhythmic fluctuations in brain activity increase across many regions. Interestingly, sensory areas of the brain remain relatively active, while regions involved in higher-level thinking and self-awareness become more suppressed. These findings suggest the brain maintains a balance during sleep: conserving energy while still preserving the ability to respond to important sensory signals. Continued research may help us better understand how sleep and brain function influence pain and fatigue.