if (rigidbody.IsSleeping())
   print("Sleeping");

using UnityEngine;
using System.Collections;

public class example : MonoBehaviour {
    void Example() {
        if (rigidbody.IsSleeping())
            print("Sleeping");
        
    }
}

import UnityEngine
import System.Collections

class example(MonoBehaviour):

    def Example():
        if rigidbody.IsSleeping():
            print('Sleeping')