Often grown as bonsai subjects, Japanese maples (Acer palmatum) hail from temperate regions that provide a distinctly cold winter. The maples need a leafless dormancy each winter to survive and grow well.
If a small-sized Japanese maple is displaying leaves from spring to fall, the plant can be grown indoors in theory. The plant must receive ample sunlight indoors to maintain its foliage and make enough food via photosynthesis to remain alive and healthy.
Since Japanese maples aren't tropical plants like other houseplants, they must endure some form of winter dormancy. After leaves drop off in fall if grown indoors, relocate the plant to an unheated garage or outbuilding so it's exposed to temperatures between 18 and 40 degrees Fahrenheit for at least 44 days.
While few pests afflict Japanese maples when they're grown outdoors, an indoor environment may stress the tree and make it more susceptible to attack from common insects. Watch out for aphids, scale, mealybugs and whiteflies.