Smell is tightly linked to emotion and attention because odor signals connect quickly with brain systems involved in memory and “good/bad” reactions. That does not mean every scent has a built-in, universal effect, but it does explain why a familiar smell can instantly make a room feel comforting—or irritating.

A scientific analysis of aromatherapy research found credible evidence that odors can affect mood, physiology, and behavior, while also pointing out a consistent pattern: psychological factors (learning, culture, personal experience) often explain the effects more broadly than simple “drug-like” chemistry.

Lavender is one of the best-studied oils for home-style aromatherapy. A systematic review focusing on inhaled lavender reported that lavender exposure was linked with reduced arousal (a calmer state) and improved sustained attention in healthy subjects, while memory findings were mixed. The review also highlighted a big reality check for consumers: studies often used different diffusion methods, different doses, and inconsistent essential-oil quality checks, making it hard to know what “lavender works” should mean in a real living room.

Other scents can push mood in different directions. In a randomized controlled study, peppermint aroma increased alertness and improved aspects of memory, while ylang-ylang increased calmness but slowed processing speed and impaired memory. That kind of “trade-off” is important: a scent that feels relaxing may not be ideal for focused work, and a stimulating scent may feel less soothing.

For home products, the science splits into two questions: does scent improve experience? and what does it do to indoor air? Oil diffusers can change the feel of a room through pleasantness, routine, and expectation (the “this is my wind-down cue” effect), and some oils may influence arousal through compounds like linalool.

But fragranced products also create real exposure for sensitive people. A population survey study reported that a substantial share of people experience headaches or respiratory problems from fragranced products, and some reported workplace impacts.

The most overhyped claim is that essential oils “treat” mental health conditions in a strong, predictable way. The better-supported claim is narrower: scents can nudge calmness or alertness, especially when the person likes the smell and the setup is consistent—while safety and tolerance limits set the boundaries.