The Relationship Between Plasticity and REM Sleep

The less plastic an animal is, the less REM sleep it has during the night. The animals born immature have much more REM sleep up to eight times as much. When a highly plastic brain drops into the world, it needs to constantly fight to keep things balanced. But when a brain arrives mostly, solidified, there's less need for it to engage in this nighttime fighting. What does our defensive activation theory mean for aliens on other planets?