Sleep is necessary for your body to rest, for relaxation and to have a break. Sleep is also important to improve your productivity and your performance. However, there are times when it is inappropriate to sleep, and there are also times when it is inappropriate to sleep for too long. When you are asleep your eyes are closed.
You no longer have your sight and your vision. To be asleep, therefore, is to lose your sight and your vision. To be asleep is to lose awareness and knowledge of your surroundings. To be asleep is to be unaware of danger. That is why God says that you must awake from your sleep and your slumber!