Yes, skin loses water. This process, known as transepidermal water loss (TEWL), happens constantly throughout the day, but accelerates at night. The average person loses approximately 300-400ml of water through their skin daily. This is a significant amount and highlights the importance of hydration for maintaining healthy skin.
Understanding Transepidermal Water Loss (TEWL)
TEWL is the evaporation of water from the skin's surface. Several factors influence the rate of TEWL, including:
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Humidity: High humidity reduces TEWL because the water vapor pressure gradient between the skin and the surrounding air is lower. In contrast, low humidity environments increase TEWL, as seen in dry winter climates. (Transepidermal Water Loss - an overview | ScienceDirect Topics)
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Temperature: Higher temperatures increase sweat production, leading to increased water loss through evaporation. (Dehydration and Heat Stroke | Johns Hopkins Medicine)
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Age: As we age, our skin loses sweat and oil glands, making it less efficient at retaining moisture and increasing TEWL. (Skin Care and Aging | National Institute on Aging)
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Prolonged water immersion: Extended exposure to water can damage the skin's barrier function, leading to significantly increased water loss. (Study shows serious skin damage after 12 hours in water ...)
Dehydration and Skin
Excessive water loss through the skin, coupled with inadequate fluid intake, can lead to dehydration. Dehydration manifests in various ways, including dry skin and reduced skin turgor (the skin's ability to snap back after being pinched). (Skin turgor: MedlinePlus Medical Encyclopedia, Dehydration: Symptoms & Causes)
Maintaining Skin Hydration
To compensate for daily TEWL, it's crucial to maintain adequate hydration by drinking sufficient water and using moisturizers to help retain moisture within the skin. (How to Tell if Your Skin Is Dehydrated - DMSI, Water, Hydration and Health - PMC)