senses

WTF Fun Fact 13444 – Sense of Smell Strongest at Night

Our sense of smell is strongest at night. So if you feel like your pets seem extra smelly, or your bubble bath is a bit too fragrant in the evening hours, you’re not just imagining things. You’re picking up on scents that are somewhat dampened during the day.

Why is smell important?

Smell influences everything from taste perception to memory formation. However, what you may not know is that our ability to detect and discern scents fluctuates throughout the day, peaking during the late hours. This might seem trivial or even surprising, but it is a fascinating aspect of our biology. And it’s linked to our circadian rhythms.

The circadian rhythm is an internal process that regulates our sleep-wake cycle. It repeats roughly every 24 hours and impacts many physiological processes, including hormone release, body temperature, and various neural functions. Interestingly, this includes our olfactory sensitivity – our ability to perceive smells.

During the daytime, our brains process a multitude of sensory inputs. The sights, sounds, and tactile sensations we encounter are processed and analyzed, taking up significant neural resources. Consequently, our sensitivity to smells is somewhat overshadowed by this barrage of information.

Why is our sense of smell strongest at night?

However, the scenario changes at night. As the environmental stimuli decrease and our focus shifts inward, our sensitivity to smells becomes more pronounced. This shift is likely due to changes in body temperature and brain activity that occur during our sleep-wake transition.

The nocturnal enhancement of olfaction has implications beyond being a mere biological curiosity. For one, it directly influences our sleep quality. We are more susceptible to disturbances from unpleasant or potent odors at night. Therefore, the significance of maintaining a fresh and pleasant sleeping environment becomes clear for a good night’s sleep.

Moreover, this increased olfactory sensitivity might have roots in our evolutionary history. Our ancestors needed to be alert to dangers like predators or fires, especially during the night. A heightened sense of smell would have been advantageous in such scenarios, leading to better survival and reproductive success.

On a practical level, this knowledge can be advantageous to various industries, especially those involved in perfume and scent manufacturing. By understanding our olfactory system’s functioning, businesses can tailor their products for maximum impact during the evening hours.

— WTF fun facts

Source: “How Smell Affects Your Sleep” — The Sleep Foundation

WTF Fun Fact 13344 – Humans Can’t Feel Wetness

The fact that humans can’t feel wetness seems ridiculous at first. You may have even read that it’s a misconception. But, technically speaking, we do not have the right “gear” to directly sense wetness – even though we all know when something is wet.

But how does that work?

Why humans can’t feel wet

Humans lack dedicated hydroreceptors – the specialized sensory receptors solely responsible for detecting wetness. As a result, wetness is not a distinct sensation for us, but rather an interpretation of multiple sensory inputs.

When a liquid, such as water, comes into contact with the skin, several different types of sensory receptors are activated. These include thermoreceptors, mechanoreceptors, and nociceptors. Thermoreceptors respond to temperature changes and can detect the cooling effect of the liquid on the skin. However, this response alone does not convey the specific quality of wetness.

Mechanoreceptors, responsible for sensing pressure and touch, provide information about the physical presence of the liquid. They detect the pressure exerted by the liquid and signal the brain accordingly. However, the activation of mechanoreceptors alone does not differentiate between wet and dry sensations.

Nociceptors, which detect pain and discomfort, may also play a role in the perception of wetness. If the liquid is extremely hot, cold, or otherwise causes discomfort, nociceptors are activated, contributing to the overall sensation. However, this response is not exclusive to wetness and can be triggered by other stimuli as well.

How we sense “wet”

Due to the absence of dedicated hydroreceptors, the brain must integrate and interpret these various signals to create the perception of wetness. It combines the inputs from thermoreceptors, mechanoreceptors, and nociceptors, along with other contextual cues, to generate the subjective experience of being wet.

While humans can recognize and differentiate wet sensations, it is important to note that wetness itself is not a distinct sensory modality. Rather, it is a perception resulting from the brain’s processing of multiple sensory inputs related to temperature, pressure, and even discomfort.

— WTF fun facts

Source: “Humans Technically Can’t Feel Wetness, And People Are Confused” — IFL Science