While our brain makes up only about 5 percent of our body weight, it consumes nearly 25 percent of our rest time energy. However, despite being a massive energy consumer, our brain is remarkably efficient. Despite containing roughly 86 billion neurons and trillions of synaptic connections, the entire organ operates on a tiny amount of electricity. It only needs about 12 to 20 watts of power to operate —roughly the same amount of energy required to power a small LED light bulb.