UV Rays and Expression Pressure May Inhibit Collagen Production During Sleep
Research by Pola Chemical Industries has revealed that daytime skin stressors like UV rays and expression pressure may inhibit collagen production driven by growth hormone during sleep. It was also confirmed that an extract of loquat leaf and lemongrass helps restore this recovery process.
📋 Article Processing Timeline
- 📰 Published: May 15, 2026 at 20:00
- 🔍 Collected: May 15, 2026 at 11:32
- 🤖 AI Analyzed: May 15, 2026 at 12:14 (42 min after Collected)
Pola Chemical Industries, Inc. (Headquarters: Yokohama, Kanagawa; President: Takayuki Katagiri), which handles research, development, and production for the Pola Orbis Group, has long focused on how daytime skin stress, such as UV rays and expression pressure, triggers wrinkles. Now, focusing on skin recovery by growth hormone during sleep, we have clarified the following two points at the cellular level:
- Stimuli mimicking daytime skin stress (UV rays and expression pressure (*1)) make it difficult for dermal fibroblasts to exhibit the protein production-promoting effect of growth hormone.
- In dermal fibroblasts subjected to stimuli mimicking daytime skin stress, a mixed extract of loquat leaf and lemongrass restores the production-promoting effect of growth hormone on procollagen (*2), the material for collagen.
This confirms the possibility that in areas prone to wrinkles from exposure to UV rays and expression pressure, the recovery effect of growth hormone may be reduced, and that plant extracts may restore this recovery ability.
*1 Compression force applied to the skin with facial movements such as laughing, talking, and moving eyebrows. It occurs especially in areas where wrinkles form and is considered a cause of wrinkle formation.
*2 A precursor to collagen. Procollagen produced within cells is secreted outside and polymerizes to become collagen fibers that maintain skin elasticity.
Relationship between Growth Hormone Secreted During Sleep and Skin Recovery
Sleep is considered important for maintaining good skin condition. The secretion of growth hormone increases a few hours after sleep begins, and it promotes protein production by binding to receptors *3 on the cell surface (Supplementary Material 1). The production of procollagen, the material for collagen that maintains skin elasticity, is also promoted within this mechanism. On the other hand, some people feel that their skin's firmness does not recover easily even if they sleep well. Therefore, in this study, we hypothesized and verified that the effects of growth hormone may not be fully exerted even when it is secreted.
*3 Growth Hormone Receptor
UV Rays and Expression Pressure May Weaken the Action of Growth Hormone
We focused on 'UV rays' and 'expression pressure,' which is the force applied to the skin with facial movements, especially in areas where wrinkles form, as daytime skin stress factors. When dermal fibroblasts were subjected to stimuli mimicking UV rays and expression pressure, the expression level of the growth hormone receptor decreased (Supplementary Material 2). It was also found that even in the presence of growth hormone, its action was not sufficiently transmitted, and protein production was less likely to be promoted (Figure 1). In other words, daytime skin stress may put a brake on the recovery of elasticity during sleep, and areas where wrinkles form may be particularly susceptible.
Next, in our search for ingredients that could mitigate the effects of stress factors, we confirmed at the cellular level that a mixed extract of loquat leaf and lemongrass restores the expression level of the growth hormone receptor (Supplementary Material 2) and restores the procollagen production-promoting action of growth hormone (Figure 2).
From this research, it is considered that to bring out the skin's firmness recovery power during sleep, it is important not only to sleep but also to care for the skin stress received during the day.
[Supplementary Material 1] About the Growth Hormone Receptor
When growth hormone, carried by the blood to various tissues, binds to the growth hormone receptor on the cell surface, a signal is transmitted within the cell, promoting the production of proteins such as procollagen, the material for collagen (Figure 3). It has also been suggested that dermal fibroblasts have growth hormone receptors.
[Supplementary Material 2] Decrease in Growth Hormone Receptor Expression Due to Daytime Stress Factors and the Action of the Mixed Extract
When dermal fibroblasts were subjected to stimuli mimicking UVB rays or expression pressure, and the expression level of the growth hormone receptor was measured, it was found that these stimuli decreased its expression. Furthermore, when a mixed extract of loquat leaf and lemongrass was added, the expression level of the growth hormone receptor was restored (Figure 4). In fact, in cells stimulated by UV rays, the procollagen production-promoting effect of growth hormone was not observed, but we confirmed that the mixed extract restored this effect (Figure 2).
In other words, it was suggested that the mixed extract makes it easier for cells to receive growth hormone even when subjected to stress factors such as UV rays and compression stimuli, thereby restoring the protein production-promoting action of growth hormone.
- Stimuli mimicking daytime skin stress (UV rays and expression pressure (*1)) make it difficult for dermal fibroblasts to exhibit the protein production-promoting effect of growth hormone.
- In dermal fibroblasts subjected to stimuli mimicking daytime skin stress, a mixed extract of loquat leaf and lemongrass restores the production-promoting effect of growth hormone on procollagen (*2), the material for collagen.
This confirms the possibility that in areas prone to wrinkles from exposure to UV rays and expression pressure, the recovery effect of growth hormone may be reduced, and that plant extracts may restore this recovery ability.
*1 Compression force applied to the skin with facial movements such as laughing, talking, and moving eyebrows. It occurs especially in areas where wrinkles form and is considered a cause of wrinkle formation.
*2 A precursor to collagen. Procollagen produced within cells is secreted outside and polymerizes to become collagen fibers that maintain skin elasticity.
Relationship between Growth Hormone Secreted During Sleep and Skin Recovery
Sleep is considered important for maintaining good skin condition. The secretion of growth hormone increases a few hours after sleep begins, and it promotes protein production by binding to receptors *3 on the cell surface (Supplementary Material 1). The production of procollagen, the material for collagen that maintains skin elasticity, is also promoted within this mechanism. On the other hand, some people feel that their skin's firmness does not recover easily even if they sleep well. Therefore, in this study, we hypothesized and verified that the effects of growth hormone may not be fully exerted even when it is secreted.
*3 Growth Hormone Receptor
UV Rays and Expression Pressure May Weaken the Action of Growth Hormone
We focused on 'UV rays' and 'expression pressure,' which is the force applied to the skin with facial movements, especially in areas where wrinkles form, as daytime skin stress factors. When dermal fibroblasts were subjected to stimuli mimicking UV rays and expression pressure, the expression level of the growth hormone receptor decreased (Supplementary Material 2). It was also found that even in the presence of growth hormone, its action was not sufficiently transmitted, and protein production was less likely to be promoted (Figure 1). In other words, daytime skin stress may put a brake on the recovery of elasticity during sleep, and areas where wrinkles form may be particularly susceptible.
Next, in our search for ingredients that could mitigate the effects of stress factors, we confirmed at the cellular level that a mixed extract of loquat leaf and lemongrass restores the expression level of the growth hormone receptor (Supplementary Material 2) and restores the procollagen production-promoting action of growth hormone (Figure 2).
From this research, it is considered that to bring out the skin's firmness recovery power during sleep, it is important not only to sleep but also to care for the skin stress received during the day.
[Supplementary Material 1] About the Growth Hormone Receptor
When growth hormone, carried by the blood to various tissues, binds to the growth hormone receptor on the cell surface, a signal is transmitted within the cell, promoting the production of proteins such as procollagen, the material for collagen (Figure 3). It has also been suggested that dermal fibroblasts have growth hormone receptors.
[Supplementary Material 2] Decrease in Growth Hormone Receptor Expression Due to Daytime Stress Factors and the Action of the Mixed Extract
When dermal fibroblasts were subjected to stimuli mimicking UVB rays or expression pressure, and the expression level of the growth hormone receptor was measured, it was found that these stimuli decreased its expression. Furthermore, when a mixed extract of loquat leaf and lemongrass was added, the expression level of the growth hormone receptor was restored (Figure 4). In fact, in cells stimulated by UV rays, the procollagen production-promoting effect of growth hormone was not observed, but we confirmed that the mixed extract restored this effect (Figure 2).
In other words, it was suggested that the mixed extract makes it easier for cells to receive growth hormone even when subjected to stress factors such as UV rays and compression stimuli, thereby restoring the protein production-promoting action of growth hormone.