Ultrashort laser pulses - that are shorter than a millionth of a millionth of a second -have transformed fundamental science, engineering and medicine. Despite this, their ultrashort duration has made them elusive and difficult to measure.  About ten years ago, researchers from Lund University and Porto University introduced a tool for measuring pulse duration of ultrafast lasers. The same team has now achieved a breakthrough that enables the measurement of individual laser pulses across a wider parameter range in a more compact setup.

Acne vulgaris is a multifactorial skin disorder with well-recognized hormonal underpinnings, yet the precise influence of menstrual cycle phases on acne severity remains insufficiently quantified using objective clinical data. This retrospective analysis provides valuable insight into the temporal relationship between menstrual cycle phases and acne flares in healthy young Indian women with mild to moderate acne. By reanalyzing data from two previously conducted clinical trials, the study uniquely leverages dermatologist-recorded global acne counts rather than relying on self-reported symptom fluctuations.

A key strength of this work lies in its structured regrouping of participants based on the number of days since the last menstrual period, allowing acne severity to be evaluated across biologically relevant menstrual phases. The findings demonstrate that acne counts were significantly higher during the late luteal and early follicular phases—corresponding to the premenstrual and menstrual periods—at baseline following a standardized washout phase. On average, acne lesion counts increased by approximately 5–6 lesions during these phases, highlighting a clinically meaningful fluctuation linked to hormonal cycling. Importantly, the menstrual phase–related effect was attenuated during the active product-use phase of the trials, suggesting that topical interventions and standardized skincare routines may mask or override hormonally driven variations in acne severity. This observation has direct implications for the design and interpretation of acne clinical trials, particularly in women of reproductive age.

Overall, this study reinforces the relevance of endocrine physiology in acne expression and emphasizes the necessity of accounting for menstrual cycle timing when assessing treatment efficacy. By providing objective, population-specific data from Indian women—a group often underrepresented in dermatological research—this analysis contributes meaningful evidence to both clinical dermatology and trial methodology, supporting more precise, cycle-aware approaches to acne assessment and management.