When rats are under long-term stress, shining red light on their heads makes a key energy part in their brain work slower, but shining infrared light makes it work faster—so different colors of light have opposite effects on brain energy.

Shining a specific kind of infrared light on the heads of stressed rats helps their brain cells produce more energy, bringing their energy levels back up to normal, like in rats that aren't stressed.

Shining a specific kind of infrared light on the heads of stressed rats makes more nitric oxide in a brain area called the hippocampus, which might help improve blood flow and energy production in their brain cells.

Shining specific colors of light on the heads of stressed rats helps them enjoy sweet water more again, making them act more like happy, unstressed rats.

Shining a specific red light on the heads of stressed rats helps lower a marker of cell damage in their blood, making it look like the blood of rats that aren't stressed at all.