3. Rosemary, Rosmarinus officinalis.

Rosemary is a plant that can help you improve your memory by 75% according to one study. The effect comes from rubbing it with your hands and then smelling its odor. Not only does it help you stay sharp, but it smells delightful and improves air quality.

4. Aloe vera, Aloe barbadensis miller.

Aloe is all business when it comes to air quality. It's listed among NASA's top oxygen-generating and air-improving plants. More oxygen in the room can help you get to sleep and stay asleep.