The steamy hot shower; the 10 minutes of respite in a day of chaos for many. Undoubtedly, the warmth of the water flushing over your skin feels wonderful. It is relaxing, it soothes aches and pains, and even helps to open the sinuses and relieve congestion. A nice warm bath or shower is truly therapeutic and has many benefits for both your physical and mental health. But how hot is too hot, and what exactly is that extra hot water doing to your skin? To answer these questions, we must have a basic understanding of the structure and function of the skin organ. Therefore, we shall begin with a brief biology lesson.
Simply stated, the human skin is composed of three basic parts: the hypodermis, the dermis, and the epidermis. Beginning at the deepest component, the hypodermis – or the subcutaneous layer – is the direct barrier between the organs and tissues underneath and the dermis. It is where most body fat is stored, and is therefore also referred to as subcutaneous fat (thanks hypodermis!). In actuality, the hypodermis is not considered as part of the skin itself, but instead part of the skin organ system which is necessary for the skin to function. It underlies the skin layers and attaches them to the underlying bone and muscle.
Next, above the hypodermis, lies the dermis. Without the dermis, the skin would lack strength and flexibility. Among other things, the dermis houses blood vessels, hair follicles, nerve endings, sweat glands, collagen fibers, elastic fibers, capillaries, and – most pertinent to the present discussion – sebaceous glands. The hypodermis supports the epidermis above and enables the skin to function and thrive. The dermis itself is composed of two layers called the reticular layer (lower) and the papillary layer (upper).
The last and outermost layer of the skin is the epidermis, which is the thickest part of the skin. The epidermis – the superficial part of skin – is what we come in contact with on a
daily basis. It serves as both a physical and a chemical barrier between the deeper skin layers (and essentially, the interior of the body body) and the surrounding environment to protect the body from intrusion and infection. Like the dermis, the epidermis is composed of different layers; and in this case there are five to be exact. Beginning at the deepest, these layers are called the stratum basale (basal layer), stratum spinosum (spiny layer), (stratum granulosum) granular layer, stratum lucidum (desquamating cell), and stratum corneum. Most of the body is covered in only 4 of these layers however; the stratum lucidum (or desquamating cell) is a thin layer of cells found only in the palms of the hands and soles of the feet. It is what helps to create their thicker texture. Most pertinent to our discussion is the stratum corneum, the outermost layer of the epidermis and therefore, the skin itself.
The stratum corneum – also known as the skin barrier, the moisture barrier, and the lipid barrier – is very important to pay attention to when caring for your skin. The stratum corneum is covered with a layer of dead skin cells (keratinous lipids), and sebaceous lipids that are produced from sebum (the body’s natural oil) secreted by epidermal cells. These form a barrier to protect the skin. Sebaceous lipids are essentially the skin’s natural fats, and can be classified at a basic level as ceramides, cholesterol, and fatty acids. To aid in understanding the function of these lipids, imagine the skin cells as tiles. If the skin cells of the stratum corneum are were tiles, then the sebaceous lipids would be the grout that fills in the gaps and reinforces the skin’s structure. When lipids are properly in place, they help to protect the skin from damage, bad bacteria, and moisture loss. However, when this lipid barrier is disturbed, many problems can ensue as the skin will be left prone to dryness, irritation, and infection. One key offender in disturbing the skin’s moisture barrier is (drum roll please)… excessively hot water.
When water is too hot, the temperature heats the natural fats in the lipid barrier causing them to melt, dislodge and be washed away. This leaves the skin with dried out dead cells and unsealed, unprotected skin since its “grout” has been disturbed. As with a too hot shower, this phenomenon can also occur when water is too hot in a bath; however, it may be exacerbated in the shower by reason of the rushing water from the shower head. This will cause more rapid lipid depletion as the heat from the water loosens the fat deposits and the mechanical rushing of water sweeps them away. This can have very negative effects on the health of the skin and cause a lipid barrier defect resulting in severe dryness. This can be even worse for those who already have conditions related to moisture barrier defects such as eczema and psoriasis. When washing your hair, too-hot water can also unleash havoc on your hair and scalp. It will strip the scalp of its lipid barrier just as it does the rest of the skin, and dry the hair itself out by removing too much of the protective sebum that has coated the hair from the scalp.
With the inherent risk to the lipid barrier that super-hot water poses, it is clear that it is not ideal when cleansing one’s body. However, since warm water does possess many positive physical and mental benefits, it begs the question: just how hot is too hot?
Dermatologists generally agree that bathing or showering water should not exceed 112 degrees Fahrenheit, as temperatures above this will greatly disturb the skin’s lipid barrier. 112 degrees is hot enough to optimally cleanse away surface dirt and bacteria with minimal risk of melting away the skin’s precious lipid barrier. Admittedly, no one wants to have to use a thermometer every time they take a bath or shower. But there is an easy way to tell without one: if you can immerse your body into the water immediately without pause, it is likely in the safe range. The water should be warm and pleasant – not uncomfortably hot. If the water is so hot that it is discomforting and you find yourself having to slowly “ease into it” of “get used to it” before you can take the plunge, it is likely a good indicator that it is hotter than necessary and advisable.
After your comfortably warm bath or shower, it is important to make the sure that your skin is protected by using a moisturizer that will protect and help restore any possible lipid depletion. Certain types of ingredients are especially effective for these purposes such as occlusives, ceramides, and humectants. Occlusives form a protective coating on the surface of your skin to simultaneously help retain moisture and prevent moisture loss. Natural oils and squalene – a natural emollient and antioxidant – are examples of natural occlusives, while petroleum jelly is an example of artificially manufactured occlusive. Ceramides are fats, such as the natural lipids found in skin. Humectants are ingredients which help to draw moisture from the air to the skin. Products that contain occlusives, ceramides, or humectants will be very effective in helping to protect and restore the skin’s lipid barrier.
Now that we’ve dabbled in a little science and learned how to protect the skin’s lipid barrier, I hope you’ll be inspired to turn down the temperature of your next bath or shower for your skin’s sake. In the long run, you’ll be glad you did!
Peace & Love,
