Many people have noticed that when we walk into the bedroom in the morning after a short absence, we feel a sense of concentrated aromathat wasn’t there the night before. This phenomenon is not directly related to hygiene – it is dictated by physics, biology and peculiarities of the microclimate of a closed room. While we sleep, our room becomes a kind of “closed ecosystem” where the accumulation of substances prevails over their dissipation.
The physics of still air
The main reason lies in the absence of circulation. During the day, we are constantly moving around the apartment, opening doors and windows, creating air currents that break up odor molecules. At night, when we are at rest, the air stagnates.
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Convection currents are slowed down due to lack of motion.
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Humidity rises due to respiration, and moist air holds odor molecules more effectively than dry air.
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Temperature regime under a blanket promotes active evaporation of volatile compounds.
Biological factors of the body
The human body continues to work actively even in sleep. Skin metabolism and respiration are the main sources of organic compounds at night.
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Sweating: A person can lose up to half a liter of fluid per night. Bacteria on the surface of the skin break down the components of sweat, releasing specific volatile substances.
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Carbon dioxide: Increasing concentration in an unventilated room makes the air “heavy”, which subjectively increases the perception of any extraneous aromas.
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Keratinized particles: Microscopic scales of skin accumulate in bedding, becoming a breeding ground for microorganisms.
The role of home textiles
Porous materials such as cotton, wool and pillow fillings, work like sponges. They do not just let air pass through, but adsorb (absorb on the surface) molecules. During 7-8 hours of sleep, the fabric has time to be saturated with the products of life and the environment. If the room has upholstered furniture or heavy curtains, they become odor accumulatorswhich are particularly pronounced under conditions of night air stagnation.
Addictive effect and morning freshness
There is also a psychological aspect called olfactory adaptation. While we sleep, our brain “turns off” the reaction to familiar odors so as not to overload the nervous system. However, once we leave the room for a couple of minutes and return, receptor sensitivity is restored. It is at this point that we suddenly become aware of the real concentration of scents accumulated overnight.
Ventilating before bedtime and using air purifiers can help to significantly reduce the molecular density of the bedroom atmosphere.
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