# Natural fibres: Down and Lyocell in moisture comparison Climate and materials Moisture absorption and sweat wicking are not the same Horsehair, wool, silk, down, and Lyocell assume different functions in the sleep system. The analysis compares sorption, liquid transport, insulation, and drying. A reliable ranking requires comparable finished constructions instead of isolated percentages for water absorption. ## Four different transport questions Sorption describes the absorption of water vapour in or on fibres. Capillary transport distributes liquid between fibres and yarns. Evaporation requires energy and a suitable vapour pressure difference. Air exchange can support discharge, provided a flow path actually exists. An absorbent filling can buffer moisture, but also store it for longer. The statement 'wicks away sweat' must therefore state whether absorption, distribution, or discharge is meant. ## Material roles in the construction Horsehair can form an elastic, airy fibre framework. Wool and silk are protein fibres with different surfaces and processing. Lyocell is regenerated cellulose. Down forms a very light insulating structure and is often used in a dense casing. The casing, quilting, and areal density strongly influence the overall result. A duvet with high water absorption is not automatically drier in the morning. Even equal filling mass does not establish a functionally identical comparison for materials with very different volumes. ## What sleep studies contribute A controlled test investigated sleepwear and bedding materials at two room temperatures. [1] Another crossover test tested various sleepwear fibres in a warm environment. [2] These works show that material and thermal context must be considered together. They do not allow for a direct conclusion that every wool blanket or Lyocell filling is superior to every down product. Specifically, data on sleepwear are not output as mattress core measurements. For the concrete STOLL question, a system comparison with identical or consciously coordinated insulation remains necessary. ## Storage capacity and drying as separate curves A sorption curve shows the equilibrium absorption as a function of climate. A drying curve shows the loss over time after defined wetting. Materials can rank differently in these two tests. For the night, buffering can be useful if sufficient discharge is possible during the day. In a permanently damp environment, the same storage capacity can be unfavourable. Therefore, a comparison should include at least one complete usage and drying cycle. The duvet is not evaluated immediately after an idealised laboratory drying if it is stored and reused under different conditions in everyday life. ## From individual material to complete construction A material characteristic value is collected on a defined sample. In the bed, however, the cover, filling, connecting layers, core, suspension, and protective layer all work together. For robust development, two test series are therefore required. In the first, one component is varied while the construction is otherwise identical. In the second, the total systems actually offered are compared. The first series explains causes; the second tests usage. Both results should remain distinguishable in the data sheet. Compression changes thickness and contact surfaces and can close flow paths. Moisture changes wetting, heat transfer, and partly mechanical behavior. A sample that performs well in a dry, new condition is therefore not yet characterized for its service life. For a comparison, pretreatment, room climate, load, sample direction, and recovery time are documented. With natural materials, variations between batches are part of the result. A single peak value does not reflect this variation. ## Aging, maintenance, and verifiable performance specifications A custom test plan should distinguish at least between the new condition, a defined stressed condition, and recovery after stress. Maintenance is carried out after the actual clearance of the product. Impermissible washing temperatures would investigate misuse rather than the intended service life. For non-washable cores, moisture changes, compression cycles, and the detachability of replaceable layers are separate questions. Measurements before and after maintenance must use the same method. The report states not only mean values but also individual values, variation, and recognizable failures. From an accelerated laboratory load, no exact everyday years are derived without a validated aging model. Furthermore, a stronger material effect is not necessarily better sleep: comfort, mobility, and maintenance effort can create target conflicts. A comprehensible performance specification therefore names the specific property and the test conditions. The subsequent user test checks separately whether this property is relevant at all for the intended group of people. Wool, silk, horsehair | Different protein fibres and structures | No uniform natural fibre characteristic curve Down | High insulation possible at low weight | Casing and moisture behaviour decisive Lyocell | Cellulose-based moisture buffering | Absorption does not guarantee fast drying Sorption | Equilibrium absorption in a defined climate | Not the same as evaporation rate Re-drying | Mass and time | Air movement and room humidity influence the trend Insulation | Thermal resistance | Same mass does not mean same thermal output A comparison is carried out once with the same thermal resistance and once as a finished sales product. Water absorption, re-drying, and contact climate are measured separately. Condition of care and room climate remain documented. A multi-night user test collects sweating and comfort without outputting sensor humidity as sweat quantity. Consultation should first clarify whether overheating, dampness, or slow drying is the problem. STOLL can then specifically coordinate insulation and moisture function. A general 'natural fibre beats synthetic fibre' or 'Lyocell beats down' would be too crude. ## Wool, silk, horsehair Different protein fibres and structures No uniform natural fibre characteristic curve ## Down High insulation possible at low weight Casing and moisture behaviour decisive ## Lyocell Cellulose-based moisture buffering Absorption does not guarantee fast drying [1] Effects of sleepwear and bedding at 17 and 22 degrees Celsius https://pubmed.ncbi.nlm.nih.gov/27217803/ Factorial test with specific clothing and bedding materials; no general fibre hierarchy. [2] Impact of sleepwear fiber type under warm ambient conditions https://pubmed.ncbi.nlm.nih.gov/31692485/ Randomised crossover test with sleepwear; not directly transferred to mattress fillings. [3] Lenzing Technologies and production https://www.lenzing.com/technology-production/technologies/ Manufacturer source on manufacturing processes; check environmental and comfort claims on the finished cover separately. This paper is a targeted narrative research as of 30 September 2026. The starting point is the specific topic question, scientific publications, and, for technical or legal questions, the relevant original sources. The Word documents provided by the client serve as templates for the professional structure and comparative presentation. Their individual statements have not been adopted without verification. This research is not a systematic comprehensive survey, a meta-analysis, or a product certification. The sources were checked via accessible publication sites, bibliographic datasets, and available excerpts. A complete article was not accessible for every source. Where only an abstract or excerpt was available, the description is limited to the information discernible therein. Figures are only mentioned within their study context; missing details are not supplemented. A phrase such as "no reliable evidence identified" describes the result of this targeted research and does not prove that no such work exists worldwide. The source numbers in the text refer to the list at the end. Directly examined findings, mechanistic considerations, and the author's own practical deductions are linguistically separated. Hypothetical cases illustrate the decision-making logic; they are not documented customer experiences. The suggested test plans are original designs. They do not establish a binding standard or a medical treatment process. Statements about a product class are not automatically transferred to individual models. For classification, the primary criterion is whether the source examines the exact question asked. A technically precise material measurement can be highly informative for a material property while saying little about sleep or long-term health. A clinical study may show a relevant benefit, but only for the group of people, construction, and duration of use studied. Proximity to the concrete question is therefore just as important as the study design. Subsequently, comparison conditions, sample size, observation duration, and potential biases are considered. Blinding is often difficult with bedding. Expectations, habituation, and the sequence of tested variants can influence results. In the case of manufacturer funding, transparency and independent replication are particularly helpful; funding alone does not decide for or against the validity of a finding. Small pilot studies are primarily used to formulate a question more precisely and to plan a larger trial. Statistical significance is not the same as practical importance. A small difference can be mathematically detectable without having a tangible benefit for the person in question. Conversely, a relevant individual improvement may remain statistically uncertain in a small group. Therefore, effect size, uncertainty, and everyday relevant endpoints are assessed together. A blanket score would obscure these differences. The interactive companion page consequently does not use fabricated health scores or simulated figures that appear like measured material data. For implementation, a concrete goal is first defined, and then the smallest reasonably testable change is selected. The initial state, construction used, and observation period are documented. Feedback should capture both the desired benefit and possible new disadvantages. If several components are changed simultaneously, the attribution of success remains uncertain. An individual comparison can improve personal selection but does not replace a general efficacy study. A supplier proof should concern the model actually offered and the intended use. Deviations in the cover, topper, base, care, or software can alter the transferability. The consultation openly states such limitations and formulates only the performance covered by data or immediate observation. For medical or legal questions, the relevant professional assessment remains necessary. The practical recommendation of this document is a basis for decision-making and not an individual diagnosis.