KOSÉ Corporation (Headquarters: Chuo-ku, Tokyo, President: Kazutoshi Kobayashi) has confirmed that social jet lag causes noticeable pores and facial redness. Social jet lag, caused by discrepancies in sleeping and waking times between weekdays and weekends, is a common modern sleep habit where one tends to stay up late only on weekends or sleep in on holidays. However, the results of this study indicate that maintaining healthy skin requires not only sufficient sleep duration but also a regular sleep habit.

Part of this research result was presented at Sleep Europe 2024 – The 27th Congress of the European Sleep Research Society (September 24-27, 2024, Spain) and at the 29th Congress of the Japanese Society of Aesthetic Science (November 2-3, 2024, Iwate Prefecture), where it received the Audience Award from the Japanese Society of Aesthetic Science.

Figure 1: The impact of social jet lag on the skin.

Background of the Research.
Lack of sleep disrupts skin turnover (renewal) and can cause dark circles due to poor circulation, which is closely related to beauty. Chronic lack of sleep is a significant issue in Japan, known as a "sleep-deprived country," and disruptions in sleeping habits are also not uncommon. For example, one may attempt to make up for sleep deprivation on weekdays by sleeping late on holidays or end up staying up late to do things that couldn't be done during the week. Such discrepancies in sleep and wake times between weekdays and weekends can disrupt the body's internal clock, leading to a state akin to jet lag, which is why it is called "social jet lag" (Figure 2).

Figure 2: Explanation of social jet lag in this study.

Social jet lag is a relatively new concept proposed by Professor Till Roenneberg, a German chronobiologist, in 2006. In recent years, not only the psychological issues caused by social jet lag have become evident, but also the physical effects such as obesity and lifestyle diseases. This study aimed to clarify the effects of social jet lag, considering the difference in central sleep times between weekdays and weekends and its impact on the skin.

Those who experience social jet lag of more than one hour struggle with prominent pores and facial redness.
To understand the relationship between social jet lag and skin concerns experienced by individuals, a survey on sleep habits and skin troubles was conducted with 67 Japanese women in their teens to twenties. The age group was chosen because social jet lag of more than two hours is particularly common among those in their twenties. The survey calculated the magnitude of social jet lag based on the sleep schedule over the past month for both weekdays and weekends (the difference in the central sleep times on weekdays and weekends) and categorized respondents into three groups based on this magnitude: 'less than 1 hour', '1 hour to less than 2 hours', and 'more than 2 hours'. The proportion of individuals experiencing 21 different skin issues was subsequently compiled (Figure 3). The result indicated that people living with social jet lag of more than one hour particularly struggle with 'prominent pores' and 'facial redness.'

Figure 3: Survey results regarding social jet lag and skin concerns.

Through a sleep intervention study simulating social jet lag, an increase in prominent pores and facial redness was observed.
Next, the effects of social jet lag on the skin were evaluated through a sleep intervention trial simulating social jet lag. 23 Japanese women in their twenties participated, and while following the usual daily rhythm of each subject, they were instructed to go to bed and wake up at generally fixed times, but only for two days a week, their sleep and wake times were delayed by two hours for two weeks (Figure 4). Skin measurements were taken on the 7th day before the intervention, the 16th day after the two-week intervention, and the 19th day after the end of the intervention to evaluate the impact of social jet lag on the skin.

Figure 4: Design of the social jet lag sleep intervention trial.

As a result, it was confirmed that a 2-hour social jet lag is associated with increased visibility of pores and redness of the face (Figures 1 and 5). This finding aligns with previous survey results regarding skin concerns among individuals in their teens to twenties, suggesting the importance of stabilizing sleep habits.

Figure 5: Changes in pore visibility and facial redness due to social jet lag.

Future prospects.
This study revealed that social jet lag, one of the disturbances in sleep habits, has undesirable effects on the skin, such as increased pore visibility and facial redness. Social jet lag is a common sleep pattern in the twenties, and the issue of visible pores is frequently mentioned among peers of the same age, highlighting the importance of stabilizing daily sleep habits. This insight will be applied to the development of future commodities and services. Continued promotion of well-being research will aim to propose new value that supports each customer's life.