The importance of nighttime on the skin

A good night's sleep is crucial for overall health and well-being, and it plays a significant role in maintaining healthy skin. Here are some reasons why respecting a healthy routine to ensure a good night's sleep is very important for your skin:

Cellular Repair and Regeneration

During deep sleep, the body undergoes a process of repair and regeneration. How does it work? During deep sleep, the body engages in DNA repair mechanisms. Skin cells can repair DNA damage caused by factors like UV radiation and environmental pollutants, reducing the risk of skin disturbance and promoting overall skin health. Additionally, to repair processes, at night, skin cells go through an accelerated natural turnover, shedding old and damaged cells and replacing them with new ones. This process is leading to the removal of dead skin cells and the promotion of a more youthful appearance. It's important to note that the quality and duration of sleep can influence the effectiveness of these two mechanisms (repair and regeneration). Factors like stress, poor sleep habits, and sleep disorders can disrupt these mechanisms and have a negative impact on skin health. Therefore, prioritizing a good night's sleep is a valuable aspect of maintaining healthy, vibrant skin.

Collagen production

Collagen is a structural protein that provides skin with its strength and elasticity. During deep sleep, the body naturally increases the production of collagen. This increase in collagen synthesis is driven by the release of hormones like human growth hormone (HGH) and insulin-like growth factor 1 (IGF-1), which are at their peak during deep sleep. These hormones stimulate fibroblasts, the cells responsible for collagen production, to create new collagen fibers. Moreover, throughout the day, the skin is exposed to various environmental stressors, such as UV radiation, pollution, and free radicals, which can damage existing collagen fibers. During deep sleep, the body engages in repair mechanisms to fix this damage. Cellular repair processes, including the synthesis of new collagen molecules, help replace and repair collagen that has been compromised. Inadequate sleep can lead to a decrease in collagen production and quality, possibly resulting in premature aging signs.

Blood Flow and Circulation

Sleep improves blood circulation: during deep sleep, blood vessels dilate and blood flow to the skin increases. This enhanced circulation delivers essential nutrients, oxygen, and growth factors to skin cells, supporting their repair and regeneration. Proper circulation helps the skin look healthy and vibrant, while poor circulation can lead to a dull complexion and uneven skin tone.

Reduce Inflammation

Sleep plays a role in regulating inflammation throughout the body. Chronic inflammation can lead to skin conditions such as acne, psoriasis, and eczema. Getting enough sleep can help keep inflammation in check and help reduce the severity of these conditions.

Hormonal Balance

Sleep is essential for maintaining hormonal balance. Hormones like cortisol, which is associated with stress, can wreak havoc on the skin if not properly regulated. Sleep triggers the release of various hormones, including cortisol but as well the “human growth hormone (HGH)”. HGH is crucial for tissue repair and regeneration, including skin cells: It stimulates the production of collagen, elastin, and other proteins necessary for skin health. Adequate sleep helps keep stress hormones in check, promoting clearer and healthier skin.

Dark Circles and Under Eye Puffiness

On this point, we will all agree that lack of sleep can lead to dark circles and puffiness around the eyes. When you're well-rested, blood vessels constrict, reducing the appearance of dark circles, and excess fluid is drained, reducing puffiness

Skin Microbiota

The effects of a bad night's sleep on the skin microbiota can vary from person to person and may depend on individual factors such as genetics, overall skin health, and lifestyle. Nevertheless, while an occasional bad night's sleep may not have a significant long-term impact on the skin microbiota, chronic sleep disturbances or poor sleep habits can potentially contribute to skin issues over time. To maintain a healthy skin microbiota, it's important to prioritize good sleep hygiene, manage stress, and maintain a balanced lifestyle.

While we have seen that the quality of night is important essential to maintain an healthy, radiant skin, we should not forget the role of the circadian rhythm which includes the night but as well the day and more importantly their pace, regularity and synchronization over the time:

• Melatonin is a hormone primarily associated with regulating the sleep-wake cycle and promoting sleep. Its secretion typically increases in the evening and peaks during the night to help initiate and maintain sleep. In a typical circadian rhythm, melatonin levels are low during the day and increase as it gets darker in the evening. Melatonin has antioxidant properties and can help protect the skin from UV radiation and free radical damage. Adequate melatonin production during sleep contributes to skin health and protection.
• The circadian rhythm influences the skin’s barrier function as well. The skin's permeability and moisture retention vary throughout the day and night according to the need. Similarly, the body temperature fluctuates according to the circadian rhythm. During sleep, body temperature tends to drop slightly. This drop in temperature can help improve skin's blood circulation, leading to better nutrient delivery to skin cells.
• Sebum production follows a circadian pattern as well. It tends to be lowest in the morning and highest in the evening.

Disruptions to this rhythm, such as staying up late or irregular sleep patterns, can lead to imbalances in oil production and potentially contribute to skin issues like acne. Formulators should consider the different needs of the skin according to the time of application of a product. It would be a non-sense to try to repair the skin during the day and to protect it against external damages at night.

Copywriter: Gwendoline Baruchet – Doctor in Biology

Editor: Dr. Baruchet, Doctor of Biology