>>287325205
Solution: Rigidbody now has a property called "sleepVelocity" which sets the threshold under which the rigid body will fall asleep.

If 0 velocity is not low enough and you need to keep it awake even then, you can use a if(rigidbody.isSleeping)rigidbody.wakup(); call in the fixedupdate, but that might get a little heavy if you have it on lots of objects as they all will have to run a check on every fixed frame.

sleepAngularVelocity The angular velocity below which objects start going to sleep. (Default 0.14) range { 0, infinity }. sleepVelocity The linear velocity below which objects start going to sleep. (Default 0.14) range { 0, infinity }.