Lifestyle, Age, and Sex Affect Several Biophysical Properties of the Skin

A woman using her smartphone.
A woman using her smartphone.
Sleep, diet, digital use, age, and sex all influence sebum content, stratum corneum hydration, and pH of skin.

Diet, sleeping habits, age, and sex may predict the nature of the skin’s sebum content, subcutaneous hydration, and pH. This is according to study data published in the Journal of Cosmetic Dermatology.

The study enrolled 300 volunteers between the ages of 20 and 69 years. Trained resident doctors administered a standardized questionnaire that asked participants about their dietary intake, whether or not they stayed up late, and time spent using electronics (eg, mobile phones and computers). A multifunctional skin physiology monitor was used to measure 3 skin biophysical properties on the dorsal hand and the forehead. A Sebumeter measured skin sebum, a Corneometer measured stratum corneum hydration, and a pH meter measured skin surface pH. Dermatologists performed all measurements a total of 3 times each to obtain an average value.

Approximately 65% of the volunteers said they go to bed after 11 pm, and up to half of respondents said they go to bed after 1 am. Only 6% of participants said they spend <3 hours a day on electronic products. More than 70% of study volunteers said they eat spicy food >3 times a week and greasy food >2 times per week. Almost half of participants reported that they eat sweets ≥2 times a week.

Participants between the ages of 25 and 29 years had significantly higher sebum content on the forehead compared with those between the ages of 20 and 24 years and >40 years. The sebum content on the forehead was also higher for those between the ages of 30 and 39 years than those between the ages of 40 and 49 years. Forehead sebum content was also significantly lower in women than it was in men.

The sebum content on the forehead significantly increased in relation to the increased number of times participants reported eating oily and spicy foods. Eating sweets twice a week was associated with the highest sebum content on the forehead compared with not eating sweets or eating sweets only 1 time per week and somewhat higher than eating sweets ≥3 times per week.

In addition, forehead sebum content was higher in the group of respondents who went to bed after 1 am compared with those who went to bed before 11 pm. Lower sebum content on the forehead was also associated with the use of electronic products for only 3 to 6 hours per day.

Subcutaneous hydration of the dorsal hand was highest in people who reported eating more sweet and oily foods. Also, subcutaneous hydration on the forehead was highest in participants who said they ate more sweet food and went to bed before 11 pm compared with after 1 am. An increased skin surface pH on the forehead and dorsal hand was associated with age, and more women than men had a higher skin surface pH. In contrast, the use of electronic products for >6 hours a day and staying up until 1 am were associated with reduced forehead pH levels.

Limitations of the study included its relatively small sample size as well as the reliance on lifestyle information that was obtained from questionnaires.

The researchers of the study wrote that the observed skin-related differences in lifestyles, ages, and sex “may be related to the individual susceptibility to skin diseases,” and the findings may have “important reference value for people to improve their skin by changing their daily behavior habits.”


Zhao C, Wang X, Mao Y, et al. Variation of biophysical parameters of the skin with age, gender, and lifestyles [published online April 25, 2020]. J Cosmet Dermatol. doi: 10.1111/jocd.13453