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The aim of this study was to investigate the development of infant and toddler sleep patterns. Data were collected on 841 children (aged from birth to 36 months) via a free, publicly available, commercially sponsored iPhone app. Analyses were conducted on caregiver recordings of 156 989 sleep sessions across a 19-month period. Detailed visualizations of the development of sleep across the first 3 years of life are presented. In the first 3 months, sleep sessions primarily lasted less than 3.5 h throughout the day. Between 3 and 7 months old, sleep consolidated into two naps of about 1.5 h in length and a night-time sleep session of about 10.5 h. Across age groups, a negative relationship was observed between the start of bedtime and the length of the night-time sleep session (i.e. later bedtime is associated with a shorter night-time sleep period). The length of daytime sleep sessions (naps) varied with age, decreasing between 1 and 5 months old, and then increasing monotonically through 28 months. Morning wake time was observed to be invariant in children aged 5-36 months. Sleep patterns are ever-changing across the first few years with wide individual variability. Sleep patterns start to develop more clearly at 5-6 months, when longer night-time sleep duration begins and sleep consolidation occurs. Daytime sleep patterns appeared to become more consistent and consolidated later in age than night-time sleep. Finally, there is greater variability in bedtimes than wake times, with bedtimes having a greater influence on night-time sleep duration.

Surfactants in skin cleansers interact with the skin in several manners. In addition to the desired benefit of providing skin hygiene, surfactants also extract skin components during cleansing and remain in the stratum corneum (SC) after rinsing. These side effects disrupt SC structure and degrade its barrier properties. Recent applications of vibrational spectroscopy and two-photon microscopy in skin research have provided molecular-level information to facilitate our understanding of the interaction between skin and surfactant. In the arena of commercial skin cleansers, technologies have been developed to produce cleansers that both cleanse and respect skin barrier. The main approach is to minimize surfactant interaction with skin through altering its solution properties. Recently, hydrophobically modified polymers (HMPs) have been introduced to create skin compatible cleansing systems. At the presence of HMP, surfactants assemble into larger, more stable structures. These structures are less likely to penetrate the skin, thereby resulting in less aggressive cleansers and the integrity of the skin barrier is maintained. In this paper, we reviewed our recent findings on surfactant and SC interactions at molecular level and provided an overview of the HM technology for developing cleansers that respect skin barrier.

PurposeTo image SDS distribution across different skin regions, to compare the permeability difference between porcine and human skin, and to evaluate the interaction between SDS and skin.MethodsFull thickness porcine and human skin was treated with acyl chain perdeuterated SDS (SDS-d25) at room temperature and at 34 °C for 3, 24 and 40 h. SDS distribution in skin was monitored by confocal Raman and IR microspectroscopic imaging. Permeation profiles of SDS-d25 in skin were derived from the band intensities of the CD2 stretching vibrations. The interaction between SDS and skin was monitored through the CH2 and CD2 stretching frequencies and the Amide I and II spectral region.ResultsSDS-d25 penetrates both porcine and human skin in a time and temperature-dependent manner, with slightly higher permeability through the stratum corneum (SC) in porcine skin. When SDS permeates into the SC, its chains are more ordered compared to SDS micelles. The secondary structure of keratin in the SC is not affected by SDS-d25.ConclusionThe spatial distribution of SDS-d25 in skin was obtained for the first time. Infrared microscopic imaging provides unique opportunities to measure concentration profiles of exogenous materials in skin and offers insights to interaction between permeants and skin.Electronic supplementary materialThe online version of this article (doi:10.1007/s11095-012-0748-y) contains supplementary material, which is available to authorized users.

Plant-derived oils consisting of triglycerides and small amounts of free fatty acids (FFAs) are commonly used in skincare regimens. FFAs are known to disrupt skin barrier function. The objective of this study was to mechanistically study the effects of FFAs, triglycerides and their mixtures on skin barrier function. The effects of oleic acid (OA), glyceryl trioleate (GT) and OA/GT mixtures on skin barrier were assessed in vivo through measurement of transepidermal water loss (TEWL) and fluorescein dye penetration before and after a single application. OA's effects on stratum corneum (SC) lipid order in vivo were measured with infrared spectroscopy through application of perdeuterated OA (OA-d34). Studies of the interaction of OA and GT with skin lipids included imaging the distribution of OA-d34 and GT ex vivo with IR microspectroscopy and thermodynamic analysis of mixtures in aqueous monolayers. The oil mixtures increased both TEWL and fluorescein penetration 24 h after a single application in an OA dose-dependent manner, with the highest increase from treatment with pure OA. OA-d34 penetrated into skin and disordered SC lipids. Furthermore, the ex vivo IR imaging studies showed that OA-d34 permeated to the dermal/epidermal junction while GT remained in the SC. The monolayer experiments showed preferential interspecies interactions between OA and SC lipids, while the mixing between GT and SC lipids was not thermodynamically preferred. The FFA component of plant oils may disrupt skin barrier function. The affinity between plant oil components and SC lipids likely determines the extent of their penetration and clinically measurable effects on skin barrier functions.

The structure of the stratum corneum (SC) and the corresponding skin barrier develops from before birth up to about 4 years of age. Large subject-to-subject variability within an age group requires a large population to observe trends in skin barrier properties over time. Barrier function, quantified by transepidermal water loss (TEWL) and SC thickness, was measured on the upper inner arm and dorsal forearm in subjects aged 3 months to 4 years (n = 171) and a subset of mothers (n = 44). The rate of skin surface area expansion as a function of age peaked before birth (∼90 cm²/week) and declined to a steady plateau (∼10 cm²/week) by 1 year of age. SC thickness increased and TEWL decreased, but did not reach adult values until 3-4 years of age. A better understanding of how skin hydration changes after birth suggests that barrier function may be related mechanistically to skin surface area expansion.

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SummaryIntroductionThe addition of hydrophobically modified polymers (HMPs) to cleansers that contain surfactants can create polymer–surfactant complexes that are less irritating to the skin than commercially available mild cleansers. Our objective was to compare the tolerability and efficacy of a test foaming liquid facial cleanser containing HMPs with a commercial liquid nonfoaming facial cleanser in women with sensitive skin.MethodsIn this randomized, prospective, double-blind, comparative study, women (n = 20 per group) with mild-to-moderate atopic dermatitis (AD), eczema, acne, or rosacea used a test gentle foaming liquid facial cleanser containing HMPs or a commercial gentle liquid nonfoaming facial cleanser daily for 3 weeks. Investigators assessed irritation and skin condition. Study subjects also assessed their skin properties and the performance of each cleanser.ResultsClinicians as well as study subjects consistently rated the test cleanser as effective or slightly more effective at improving symptoms than the commercial cleanser, although no significant differences between groups were observed. At weeks 1 and 3, respectively, more users of the commercial cleanser reported irritation (20% and 10%) than users of the test cleanser (5% and 5%). In addition, subject self-assessments of skin condition and cleansing properties were slightly more improved with the test cleanser than with the commercial cleanser.ConclusionsBoth the test foaming cleanser containing HMPs and the commercial nonfoaming cleanser were effective and well accepted by most women in the study. Improvements were observed by both clinicians and subjects in the group using the test cleanser containing HMPs in all evaluated skin categories.