scent, alertness and staying awake at the wheel

Canadians spend a fair amount of time in the car, and drowsiness at the wheel is a genuine safety problem: tired driving impairs reaction time in ways that are measurably similar to alcohol.

there is research suggesting that certain scents help alertness. it is worth knowing about, and it is worth being honest about how far it goes.

what the research suggests

peppermint and cinnamon are the two most studied, and studies have found modest improvements in alertness and reduced fatigue ratings among drivers exposed to them.

citrus, particularly lemon, shows up in similar work.

going the other way, lavender and chamomile are associated with relaxation, which is exactly what you do not want on a long night drive.

the honest caveat

these effects are small. they are the difference between slightly more alert and slightly less, not the difference between safe and unsafe.

nothing in a bottle substitutes for sleep. if you are fighting to stay awake, the answer is to stop driving, not to change the air freshener. that is not a disclaimer, it is the main point.

the things that actually work

• pull over and sleep for twenty minutes. nothing else comes close.
• caffeine, which takes about twenty minutes to take effect, so have it before the nap rather than instead of it.
• cool air and fresh air. warm still air makes drowsiness worse, which is worth remembering in a car with the heater on in February.
• plan around it. the worst hours are the small ones and the mid-afternoon dip, and both are predictable.

one thing that is not about scent at all

if your car smells sweet and the windows fog up persistently, that is not an air freshener question. that is coolant leaking from the heater core into the cabin, and you are breathing it.

same if you can smell exhaust inside the car. both are worth having looked at promptly rather than covering up.