Why bad smells around the house, like kitchen garbage and sweaty gym bags, can be a sign that you’re stressed

The trash can stinks, the fridge stinks, and the smell of sweaty gym gear is overpowering…but relax.

Maybe the house doesn’t need cleaning yet, maybe you’re just a little stressed.

A study found that when we are stressed, our sense of smelling unpleasant odors is enhanced.

But our sensitivity to pleasant or neutral smells is unchanged.

It is believed that the release of the “stress hormone” cortisol in the “fight or flight” mode allows us to better detect bad odors that may pose a threat.

The researchers asked 40 men and women to complete a stressful speaking activity and a math test, then measure how well they perceived pleasant, neutral and unpleasant smells.

The pleasant scent was citronellol, which smells of lemongrass and rose, while the neutral scent was 2-heptanol, which was described as “earthy, oily.” The unpleasant odor was 4-methylpentanoic acid, which smells like sweaty socks.

Participants were also asked to come to the laboratory a week before or a week later for a control session in which they performed the same odor recognition tests, but without first participating in the stress-inducing tasks.

The researchers at Southwest University in China said: “There was a significant effect of stress on olfactory sensitivity to the unpleasant odor. However, there was no significant effect of stress on sensitivity to pleasant or neutral odors.”

A study found that when we are stressed, our sense of smelling unpleasant odors is enhanced

The group added: “A state of hypervigilance following acute psychological stress may increase the sensitivity of the olfactory system to detect potentially threatening stimuli, which is influenced by stress-related cortisol reactivity.”

The results of the study were published in the journal Hormones and Behavior.

Dr Andrew Thomas, a psychologist and lecturer at Swansea University who was not involved in the study, said: “These results make sense from an evolutionary perspective.

Cortisol is a stress hormone released when the body reacts to threats as part of the fight-or-flight response.

“Fight or flight and freeze have numerous effects on the body to prepare it for threats.

“If we assume that what these researchers found is true for larger samples, it suggests that the stress response also increases our sensitivity to unpleasant smells.

“The odors we find offensive are usually odors that indicate the presence of something harmful, such as bacterial growth.”