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A new AWI-funded study has investigated the effect that wool, cotton and polyester sleepwear each have on the sleep quality of older adults (aged 50-70) under warm conditions.
Consistent with previous research in relation to younger adults, the new research found that a better night’s sleep is achieved when sleeping in wool.
Shifts in global demographics are working in favour of the wool industry.
One aspect of this is the growth of the ‘working age empty nester’ segment – those older adults who are maintaining income (by working later in life) but have fewer dependents (their kids have left home) and hence have higher than average disposable income.
As their bodies get older, people in this segment have changed their consumption patterns towards things like fitness and health care.
As we all know, there are plenty of negatives associated with an aging body (many of them involving gravity!) but one aspect of note for this article is that quality of sleep tends to decrease with age.
The sleep of older adults compared to younger adults is more fragmented and lighter with reduced duration of deep sleep.
Furthermore, warm environments easily disrupt sleep and this is especially the case in older adults, who have been shown to have poorer thermoregulation than younger adults.
Sleepwear plays several crucial roles in thermoregulation. Fabrics made from natural fibres allow higher rates of heat and moisture transfer than synthetic fibres thereby promoting thermal comfort.
A dry wool fibre, for example, absorbs moisture vapour up to about 35% of its dry weight in saturated air, whereas cotton can absorb around 24% and polyester fibres below 1%.
The effects of sleepwear fibre type on the sleep of older adults have never previously been studied.
AWI therefore recently funded a study by the University of Sydney to compare the effect on sleep quality of wool, cotton and polyester sleepwear, in warm conditions (30ºC and 50% humidity) for participants aged 50-70 years old.
Thirty-six healthy participants (18 males and 18 females) participated in the trial with polysomnography, skin temperature, microclimate temperature and relative humidity measured.
They completed four nights of study. Sleepwear fabrics of either single jersey Merino wool, cotton or polyester were used.
The sleepwear was long sleeve tops and long pants – participants slept without a blanket or a sheet.
THE RESEARCH RESULTS
Sleep benefits for wool compared to cotton and polyester sleepwear were observed during the study.
The key findings were:
- Sleeping in wool resulted in less fragmented sleep compared to sleeping in other fabrics, especially between wool and polyester sleepwear.
- Sleeping in wool reduced the time taken to get to sleep compared with sleeping in cotton and polyester for older participants aged≥65 years.
- Sleeping in wool resulted in less total wake time for poor sleepers after sleep onset, compared to sleeping in cotton. Overall, wool performed better than cotton and polyester for the majority of sleep quality parameters.
COMPREHENSIVE BODY OF RESEARCH
With older adults willing to spend above average on products that will maintain their health, the big characteristic of these products that these people want is quality – ‘less but better’ – which is perfect for wool.
Furthermore, higher average summer temperatures and the frequency and intensity of hot days are now observed in Australia and globally.
The use of air-conditioning to control temperature has financial and environmental costs and is also associated with negative effects on human health.
“It is therefore of interest to investigate alternative healthy, environmentally-friendly and cost-effective strategies for older adults to cope with sleeping under warm ambient conditions,” says AWI Program Manager, Fibre Advocacy & Eco Credentials, Angus Ireland.
“A previous AWI-funded study undertaken by the University of Sydney investigated the influence of sleepwear on the sleep quality of healthy young participants – it found that wearing Merino wool sleepwear significantly reduced the time for the participants to fall asleep, thereby tending to increase total sleep time.
“And this new study, focused on older adults, has also shown that wool sleepwear promoted higher quality of sleep than either cotton or polyester sleepwear.
“The great value of these research investments on behalf of Australian woolgrowers is that we are now building a very solid and contemporary body of scientific evidence which supports claims that wool is beneficial to a good night’s sleep, which should help build consumer demand for wool.”
While this study has shown wool sleepwear promotes better sleep at the higher ambient temperature, particularly in older adults and poor sleepers, future studies may also identify benefits of sleeping in wool for people such as menopausal women who often experience hot flushes and disturbed sleep, and shift workers who have disrupted circadian timing.
For more stories from Beyond the Bale head to www.wool.com/btb