Send subliminal messages

“If you have a small room, the smell of green apple or cucumber makes you perceive it as larger. For the bedroom, lavender helps you go to sleep. In the den, you could have a mixed floral smell, which we found increases learning speeds.”

Be sparing

“If the same intensity of odor is present for a long time, you’ll adapt to it and won’t detect it at all. You want puffs, delivered intermittently.” So use a scented candle instead of a continuous air freshener.

Inhale memories

“Reexposing yourself to a memorable odor, like from your wedding” — say, the flowers in your bouquet — “will help you recall the event and all the emotions surrounding it.”

Dial up or down the intensity

“Women have a better ability to smell than men, so men might choose a much stronger odor. As you age, your sense of smell drops about 1 percent a year, so about half of those over 65 have a reduced ability to smell. You want to use a scent level that’s appropriate not only for you but also for other people in the household.”