Skin hydration

Main

Skin hydration refers to the water content within the skin cells and the skin's ability to retain that moisture. Water is stored in the dermis, the layer of skin below the surface, and is transported to the epidermis, the outer layer of skin. Hydration is maintained through a combination of drinking water, which hydrates from the inside out, and using topical skincare products with humectants like hyaluronic acid, which attract water to the skin.

Proper skin hydration is achieved by:

• Drinking adequate water throughout the day

• Using gentle, non-stripping cleansers

• Applying hydrating skincare ingredients like hyaluronic acid, glycerin, and urea

• Protecting the skin's natural lipid barrier with moisturizing ingredients like ceramides

Skin hydration is measured by corneometry, which assesses the water content in the stratum corneum (the outermost layer of the epidermis). Dehydrated skin doesn't just feel dry and tight - it can lead to a weakened skin barrier, making skin more prone to irritation, sensitivity, and accelerated aging.

While humectants like hyaluronic acid are generally beneficial for attracting moisture, they can potentially draw water out of the skin in very dry environments if not combined with occlusive ingredients. So during winter months, it's best to use humectants alongside richer, more protective creams.

Terms

• Dermis: The layer of skin below the surface that stores water and transports it to the epidermis.

• Epidermis: The outer layer of the skin that receives hydration from the dermis.

• Humectants: Water-loving ingredients like hyaluronic acid and glycerin that attract moisture to the skin.

• Hyaluronic acid: A powerful humectant naturally found in the skin that can hold up to 1,000 times its weight in water. Used in skincare to hydrate and plump the skin.

• Lipid barrier: The protective barrier in the stratum corneum composed of lipids (oils) that seal in moisture. Also called the moisture barrier.

• Stratum corneum: The outermost layer of the epidermis composed of dead skin cells and lipids. Plays a key role in retaining skin hydration.

Analogy

Skin hydration is like watering a plant. The water is stored in the soil (dermis) and is drawn up into the leaves and flowers (epidermis). If the soil doesn't have enough water, or if the plant is in a very dry, hot environment and the water evaporates too quickly, the leaves will start to wilt and the plant will suffer. Similarly, when the skin lacks water or the environment draws too much moisture out, skin will look dull and feel dry, tight, and uncomfortable.

Misconception

Many people think that drinking a lot of water is enough to hydrate the skin. While proper water intake is important, it's not the only piece of the puzzle. The skin also needs topical hydrating and moisturizing ingredients to attract water and seal it in. People with naturally oily skin may also assume their skin is hydrated because it looks shiny, but in reality, their skin could still be dehydrated if it's lacking water.

History

1. Ancient times: Natural ingredients like honey, milk, and olive oil were used to moisturize the skin.

2. Early 1900s: Hydrating ingredients like glycerin and hyaluronic acid were discovered and incorporated into skincare.

3. 1950s-1960s: The role of the skin's lipid barrier in retaining moisture was identified, leading to moisturizers containing lipids.

4. 1980s-1990s: Skincare became more specialized, with targeted products for different skin types and concerns, including dehydration.

5. 2000s-present: Scientific advancements have led to a better understanding of skin hydration and more sophisticated ingredients and delivery systems to optimize skin's moisture levels. There is an increased focus on maintaining skin hydration as an important aspect of overall skin health and anti-aging.

How to use it

1. After cleansing, apply a hydrating toner or essence containing humectants like hyaluronic acid or glycerin to damp skin. This will add an extra layer of hydration and help following products absorb better.

2. Layer on a hydrating serum with additional humectants as well as soothing, nourishing ingredients like panthenol or niacinamide. Ingredients like ceramides will also help support the skin's moisture barrier.

3. Seal everything in with a moisturizer appropriate for your skin type. Look for ingredients like glycerin and hyaluronic acid to add hydration, plus occlusive ingredients like dimethicone or shea butter to prevent water loss. If you have oily skin, opt for a lightweight lotion, while dry skin types may prefer a thicker cream.

Facts

• The average person has about 300 million skin cells, and each one needs water to function properly.

• The skin contains approximately 30% water, which helps it maintain a smooth, plump appearance.

• Skin hydration levels decrease by an average of 6% per decade after age 20.

• Transepidermal water loss (TEWL), the process by which water evaporates from the skin's surface, increases by 30-50% in winter months due to low humidity and harsh weather conditions.

• Hyaluronic acid is found naturally in the skin, but levels decline with age, making topical application beneficial for maintaining hydration.