Research has revealed a number of health benefits for Australian Merino including improved sleep for most people, increased weight gain and reduced risk of SIDS for babies, and lower incidence of microbial infection for hospital patients.

General health benefits

The main health benefit of Merino for the general population is improved sleep. This can be attributed to the incomparable ability of Merino to maintain a comfortable micro-climate between body and bedding.

Superior insulation

The fineness of the Merino fibre and its natural crimp create millions of tiny air pockets which help make Merino fabrics much better insulators than synthetic textiles. This helps protect a sleeping body from the external changes in temperature that might wake someone sleeping under synthetic bedding.

Humidity control

At least as important as Merino’s ability to insulate the sleeper from temperature extremes is its ability to buffer changes in humidity. While synthetics have negligible ability to absorb moisture, Merino can absorb up to 35% of its own weight in liquid. This means that in the conditions of high humidity that can exist under bedding, Merino has the ability to draw off vapour from the micro-atmosphere and so reduce the uncomfortable feeling of clamminess that can be so disruptive to sleep. (Fig 1)

Moisture transport

In addition, Merino has a superior capacity to absorb liquid sweat from the skin and evaporate it to the atmosphere. In fact, in CSIRO testing, it was shown to transport 27% more uncomfortable sweat away from the skin than a synthetic fabric. Not only does this mean that Merino is better at keeping the skin dry and comfortable during sleep but this process of evaporation actually produces a drop in temperature which acts to make the atmosphere under bedding even more comfortable.

Merino vs acrylic-fibre-cotton blankets

In 1986, Umbach at the Holstein Institute in Germany verified the health benefits of Merino when he carried out sleep experiments using wool blankets and other blankets made of an acrylic-cotton blend.

Less hot and clammy

It was found that the Merino blanket provided 8-20% higher thermal insulation and absorbed 50% more sweat, confirming the theoretical expectations. What’s more, under the acrylic-cotton blanket, 75% of subjects felt uncomfortably hot and 88% felt clammy while the comparable figures for the wool blanket were only 38% and 50%. (Fig 2)

Overwhelming preference for Merino

On a scale of 1 to 5 (where 1 is very good and 5 is inadequate), subjects gave the acrylic blanket a rating of 3.9 and only 25% of them said they would be prepared to sleep under it. By comparison, they rated the wool blanket 2.1 and 75% said they would be prepared to sleep under it even in a warm climate.

Lower heart rate

In a less predictable finding, Umbach discovered that the average pulse rate of subjects sleeping under the wool blankets was “normal” at 60 beats per minute while the average for those under the acrylic-cotton blanket was an erratic 80 beats per minute, indicative of the higher level of thermal distress.

Effect of Merino underlay on sleep

In a study by Dickson in 1984, he found that subjects sleeping on Merino underlay had over 20% more periods during which no body movement occurred, compared to those sleeping without the underlay (a period is deemed to be 15 minutes). The subjects on the Merino underblanket also reported feeling better in the morning, and up to 60% were extremely enthusiastic about its use.

Benefits of Merino for babies

Medical studies have proven that Merino improves the sleep patterns of babies resulting in increased weight gain and generally improved levels of contentment. It has also been shown that swaddling a baby in Merino is likely to lower the risk of SIDS.

Effect of Merino on infant sleep

Various studies have found that putting babies directly on Merino bedding lowers their rate of activity and produces a deeper more restful sleep, a fact confirmed by faster rates of growth. At the Cambridge Maternity Hospital in 1979, Scott and Richards investigated the effects of Merino bedding on low-birthweight babies and found that they gained an extra 10g a day compared to babies that weren’t on Merino. Scott also performed a similar study of infants at home and found that babies sleeping on Merino settled more quickly, cried less and fed for longer periods. Parents of infants who were sleeping on Merino also reported a stronger sense of parent-baby bonding.

Merino and SIDS

A number of studies have shown that swaddling infants tends to reduce the likelihood of Sudden Infant Death Syndrome (SIDS). Since overheating has been identified as a key factor in many cases of SIDS, there is a strong case for using Merino as the swaddling cloth because of its previously noted ability to regulate heat and humidity.

Reduced allergies

Demoly and Bousquet found that bedcover choice can also influence the prevalence of childhood respiratory allergies. Dust mites prefer hot humid environments and it has been shown that Merino is much better at lowering both temperature and humidity than synthetics. To prevent the proliferation of mites it is also necessary to clean regularly and this is much easier with a wool blanket than a synthetic duvet in a cotton cover.

Fire resistance

Another way in which Merino helps safeguard childrens’ health is its fire resistance. Merino requires an extremely high temperature before it will ignite and also demands an oxygen level higher than that found in the atmosphere for flame to be sustained. It never melts which means it can’t stick to the skin the way many synthetics can, and it contains natural fire retardants so that even if it does catch fire Merino tends to be self-extinguishing.

Benefits of Merino for hospital patients

Benefits like improved sleep through reduced heat and humidity, and fire resistance also serve to enhance the well-being of hospital patients. However there are other benefits that are likely to aid the recovery of someone recuperating from injury or illness.

Anti-microbial

Bacteria tend to be attracted to smooth positively charged surfaces like those of synthetic fibres rather than the scaly, neutrally charged surface of the Merino fibre. This anti-microbial quality of Merino was confirmed in a five-month trial conducted at the Gosford Hospital and Orana Nursing Home in New South Wales, Australia. The study found that while no bacterial colonies were found in the Merino blankets, fifty colonies were found in the cotton sheets.

Ease of washing and durability

Making Merino an even more sensible option for hospitals is the fact that it can be washed at high temperatures. While cotton can also be boiled to rid it of bacteria, it can only withstand 60-120 wash cycles compared with the 600-700 reported by the Gosford Hospital Laundry Manager.

Reduction of bedsores with underlays

A study in 1964 showed that fleecy underlays aided in the prevention of ulcerative pressure or ‘bed’ sores. Hospital trials indicated that when a patient slept on a Merino underblanket it more evenly distributed their weight, lowering pressure on sensitive areas. As a result, patients reported a lower incidence of ulcers on the normally vulnerable regions of shoulders, hips and ankles.

Summary

Merino’s superior insulation, micro-climate control and moisture transport have been proven in numerous trials to produce improved sleep patterns and general wellbeing. Babies on Merino bedding have been shown to settle more quickly, cry less and gain weight more quickly, while those swaddled in Merino are less likely to suffer the overheating that has been linked to SIDS. Hospital patients benefit from Merino’s anti-microbial qualities and its ability to sustain repeated washing at bacteria-killing temperatures, while Merino underlays have been shown to reduce the incidence of bed sores.

Sources:

• Santé Prévention Recherche Information Médicales, Box, VI, 2004,”Effect of wool blanket use on sleep”
• Santé Prévention Recherche Information Médicales, Box, VII, 2004, “Effect of wool blanket use on children”
• Santé Prévention Recherche Information Médicales, Box, IX, 2004, “Wool blanket in hospital environment”
• Demoly, P. and Bousquet, J., 2000. Dormir avec une couverture: des incidences inattendues sur la santé. Colloque Santé et Vie quotidienne, Ecole de Médeccine, Paris pp 26-30
• Scott, S. and Richards, M. 1979. Nursing low-birthweight babies on lambswool. Lancet, pp 1028
• Scott, S., and Richards, M. 1983. Lambswool is safer for babies. Nursing low-birthweight babies on lambswool. Lancet, pp 556.
• Scott, S., Cole, T., Lucas, P. and Richards, M. 1983. Weight gain and movement patterns of very low birthweight babies nursed on lambswool. Lancet, pp 1014-1016.
• Dickson, P.R. 1984. Effect of a fleecy woollen underlay on sleep. The Medical Journal of Australia, Jan 21, 87-89.
• New Zealand Wool Board. 1964. Sheepskin rugs for nursing. Wellington: New Zealand Wool Board.
• Pressley, T.A. The use of textiles in hospitals. CSIRO Division of protein chemistry, Melbourne.
• Pressley, T.A., Rubbo, S.D., Stratford, B.C. and Dixson, S. 1960. Vehicles of transmission of airborne bacteria in hospital wards, The Lancet, 397-400.
• Pressley, T.A., 1961. CSIRO Division of protein chemistry, Melbourne, “Blanket for institutional use”, Educational bureau NAILM.
• Umbach, K.H. 1986. Comparative thermophysiologocial tests on blankets made from wool and acrylic-fibre-cotton blends”, J. Text. Inst., No3. Paper presented at conference entitled “Comfort in Textiles” organised by the Manchester and district section of the Textile institute and held at the University of Manchester Institute of Science and Technology on 4 April, 1984.