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

	rigidbody.sleepAngularVelocity = 0.1;

using UnityEngine;
using System.Collections;

public class Example : MonoBehaviour {
    void Example() {
        rigidbody.sleepAngularVelocity = 0.1F;
    }
}

import UnityEngine
import System.Collections

public class Example(MonoBehaviour):

	def Example() as void:
		rigidbody.sleepAngularVelocity = 0.1F