Global surveys have revealed that the novel coronavirus (COVID-19) pandemic has drastically changed our daily lives, affecting our sleep patterns and biological clocks. For example, it has been reported that people's quality of sleep has deteriorated due to increased mental stress, and their biological clock has been disturbed due to a late-night lifestyle. The condition of one's sleep and biological clock is closely related to health maintenance, and their malfunction is known to lead to mental disorders and disease, including those related to lifestyle. The use of scents to promote sleep dates back to ancient Egyptian times, and the latest brain and neuroscience research has led to a better explanation of the physiological effects of scents. In line with this, the development of new therapeutic agents is underway. In addition, the relationship between the biological clock and olfaction has been investigated, and new possibilities for scents have been suggested. In this review, we will outline the role of scent on sleep and the biological clock, including its effect on improving biological clock disturbances.

Recently many people have begun choosing their original wavy hair instead of straightening their hair. However, they have to put a lot of effort into hair styling as curls are difficult to control. One of the important requirements for beautiful wavy hair is well-defined curl alignment as curls with lustrous and frizz-less appearance are often preferred. Therefore, new approaches to make well-aligned curls are valuable. We focused on the curvature of single hair fibers in curl bundles. The result of curvature measurement showed that well-aligned wavy hair has a narrow curvature variation. We have found that Sodium 2-naphthalene sulfonate (SNS) can decrease curvature variation. By applying SNS to wavy hair, each fiber spontaneously harmonized in curls, which result in well-aligned wavy hair with luster and less frizz. The relationship between curvature and hair structure was then investigated and it was found that the more bilateral distribution of two types of cortical cell was seen in the higher curvature part. A mechanical model was proposed to explain how SNS straightens hair and decreases curvature variation reflecting the distribution of two types of cortical cell. This technology would be a breakthrough which releases consumers from daily stress due to styling and making their original hair shape more attractive.

One of the significant concerns about hair coloring is the color fading of the dyed hair. It is difficult to keep the ideal hair color for a long time. There are various possible causes, and the pigment outflow when washing the hair with shampoo is considered to be particularly large. In recent years, hair care products for dyed hair have been launched on the market; however, the color-lasting effect is often inadequate for damaged hair. It is thought that this is because the cuticle of damaged hair is turned over and the effect of pigment outflow during hair washing is more pronounced. Therefore, we aimed to develop a shampoo which inhibits pigment outflow by coating the hair surface and repairing the cuticle during hair washing. We focused on polyquaternium-104, a silicone resin which is cationic and has rubber-like flexibility, expecting high adhesion and repair ability for the cuticle. As a result, it was found that the shampoo containing polyquaternium-104 has high cuticle coating and repairing effect. Subsequently, we examined the ability to inhibit hair color fading, and found that it was highly effective compared to general cationic polymers by visual inspection and color difference measurement. Furthermore, it was revealed that the smoothness of the hair surface after shampoo and conditioner was improved by using shampoo containing polyquaternium-104. This interesting result suggests that polyquaternium-104 has not only fading inhibition ability but also efficient adhesion ability of conditioner.

It is the manufacturer's responsibility to prevent microbial contamination during the cosmetic product life cycle; therefore, it is imperative that cosmetic formulations have adequate preservative efficacy. The preservative efficacy of a formulation is evaluated using preservative efficacy testing (PET), which usually requires a test period of about one month and failing PETs may lead to product launch delays. In order to detect formulations for which preservative measures had failed in the early stages of product development, we conducted a predictive analysis of preservative efficacy using artificial intelligence (AI). The training data for AI included formulation ingredients, such as the concentrations of ingredients of cosmetic leave-on care products like toners, emulsions, and creams, quasi-drugs, and pharmaceuticals as explanatory variables, and PET test results provided with Staphylococcus aureus as the objective variable. Among the formulation ingredients, the aqueous phase concentrations of preservatives, alkanediols with three or more carbon atoms, and ethanol, which act as preservative boosters, are theoretically calculated and they are used as explanatory variables. With the machine learning software “Prediction One”, a binary classification model was created to predict the efficacy of preservative approaches against S. aureus, and the prediction accuracy was verified by cross-validation. We were able to reach the possibility of predicting failures of preservative formulations against S. aureus with AI.

It is known that commercial cleansing creams undergo a phase inversion from O/W (Oil in water) to W/O (Water in oil) during use, and that the viscosity of the creams decreases, resulting in a marked change in the texture. We attempted to establish a new measurement method to evaluate the change in the texture of cleansing creams caused by the phase inversion on a rheometer. As a result, we found that viscosity changes corresponding to usability could be observed by performing a new measurement (phase inversion mode) in which the sample was measured while being applied by shearing for 1 min, then the upper plate was raised and exposed to dry air for 1 min, and the measurement was repeated 10 times with the plate returned to its original position again. The results of the impedance and the small-angle light scattering (SALS) measured synchronously with the rheological measurements revealed that phase inversion from O/W to W/O during applied shearing.

Glycerol is widely used as a moisturizer in personal care products. However, there are few reports on the moisturizing mechanism and moisturizing effect of combining glycerol with other moisturizers. In general, moisturizers function on binding with moisture in the stratum corneum. Therefore, it is thought that the moisturizing effect also changes depending on the combination of moisturizers. In this study, we evaluated the moisturizing effect of moisturizers combined with glycerol in vivo. In this study, we selected natural moisturizing factors (NMF) such as urea, sodium lactate and sodium pyrrolidonecarboxylate as moisturizers to combine with glycerol. The moisturizing effect was evaluated by measuring the increased amount of stratum corneum water content when the moisturizer aqueous solution acted on the skin by the capacitance method. As a result, it was found that the moisturizing effect is synergistically improved by using glycerol in urea, which is one of the NMFs.