Hearty Smells

By Laura Hospitál on Jul 18, 2015

This science project was done by Donna, who is a student at Texas School for the Blind and Visually Impaired (TSBVI).


Does smell affect heartrate and cause stress?
Note: why does heartrate speed up when we are stressed?
  • Lavender
  • Lemon oil
  • Coconut oil
  • Vineger
  • Tea tree oil
  • Cinnamon


Odor facts:  Younger people are more sensitive to odors than older folks. Women are more sensitive to odors than men. Non-smokers are more sensitve to smell than smokers. People with an empty stomache are more sensitive to odors than people who just ate. People are more sensitive to odors in the morning than in the evening.
Odors can affect behavior;  Mood, level of alertness, levels of anxiety, level of stress.
Positive or pleasant odors can have beneficial health effects;  positive, happy mood, easier to learn and work, easier to sleep, more resistant to pain, fewer headaches or stomach aches.
Unpleasant or Negative odors can have a negative health impact;  nausea, headaches, depression, increased anxiety, Elevated blood pressure, decrease in physical energy, compromise immune system, physical discomfort, increase in anger and stress, and muscular, control problems fatigue and confusion.


If someone smells a pleasant smell I belive that their heartrate would heartrate and blood preasure would calm or slow down. If someone were to smell an unpleasant smell I blelive that their heartrate and blood preasure would increase.
As I researched this topic, it became more complicated because not all people consider the same smells pleasant or unpleasant.  For instance, one of my volunteers found tea tree oil to be a pleasant smell, even though I had chosen it as an example of an unpleasant smell.


  • An image of the different scents used in this project digital heartrate reader
  • lavender essential oil
  • coconut oil
  • tea tree oil
  • cinnamen essential oil
  • vinegar
  • lemon essential oil
  • blindfold
  • 6 jars with lids
  • volunteers



Step 1. Ask student if they are allergic to anyting. Blind fold the person alone in a room allow 2 minutes for  student to calm down befor taking measurments. Step 2. Take heartrate before procedure begins. Step 3. Have person smell lavender 5 seconds thenn lemon, next vinegar, after coconut oil, then tea tree oil, and finaly cinnamon. Step 4. Between each scent record heartrate 7 seconds after smelling the scents. wait 5 minutes between each scent.  

Taking a student's pulse


Average  change of heartrate in beats per minute Cinnamon – Decrease of 5.8 BPM Lavendar -  Decrease of 1.1 BPM Lemon – Increase of 2.5 BPM Coconut Oil – Increase of 3.9 BPM Tea Tree Oil – Increase of 5.2 BPM Vinegar – Increase of 6  BPM             Graph produced by the student of her results   Comments from Students: About Vinegar: “That hurt my tonsils and tongue.” “Oh no miss, that burned my nose Miss” “This one is rank.”   About Tea tree oil: “That stinks.  I hate you, you.” “ This smells like a nursing home.”   About Lemon: “That reminds me of that that cleaning stuff.” About Coconut oil: “I can’t smell nothing , It’s faint.”   About cinnamon: “Smells like a sports place.” About lavender: “Am I going to die because my heart dropped 2 beat  


My results were inconclusive as I discovered that smells are very personal.  What is a pleasant smell for one person may be an unpleasant smell for another.  



Other scents were considered including sulfur which smells like rotten eggs.  

NGSS Standards:

Plan and conduct an investigation individually and collaboratively to produce data to serve as the basis for evidence, and in the design: decide on types, how much, and accuracy of data needed to produce reliable measurements and consider limitations on the precision of the data (e.g., number of trials, cost, risk, time), and refine the design accordingly. (HS-ESS2-5)
hearty smells collage
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