Yes to keep a rabbit healthy the rabbit needs to be outdoors in real sunlight as much as possible.
It's okay to bring the rabbit inside especially when it's cold out but try putting the rabbits cage near a window that gets lots of sunlight through it to allow the rabbit to catch the UV rays and stay healthy.
When possible take the rabbits cage outside into the sunshine so that they'll be happier and healthier.
When there's no sunlight try to provide some artificial light for the rabbits.