Do you have a walk-in-robe or an ensuite bathroom? DS co-sleeps with us atm and we leave the light on in either the robe or the bathroom and close the door to the point it is almost closing - it lets enough light in that you can see where you are going and doesnt disturb DS even when putting to sleep. You could then if DH wants to read simply open the door more - theoretically cause the light is already on it shouldnt disturb your DS- Does that make sense?