No one can live without sleep.
If the average night's sleep is eight hours, people sleep for one-third of their life.
Today, the world is so full of stress that you hear your colleagues, spouse, and others say, “I can't sleep well,” “I need sound sleep,” or “I don't feel refreshed when I wake up.”
Back in 1995, Aisin Seiki launched a gel mattress. Its body pressure dispersing nature made it popular.
Soon, low rebound urethane mattresses offering a similar feeling started to quickly replace gel mattresses. Aisin’s market share dropped sharply, by almost 30% of the sales peak.
“For sure, the Gel Mattress we released to the market built a new category in bedding where only spring mattresses and waterbeds were the choices available.”
“But now, those made of low rebound urethane are catching up, and soon enough, unfortunately, will take more market share. We need to do something to move ahead.”
A sales person reacted.
“You are suggesting we would better go with low rebound mattresses, too?”
One from Development Dept. opposed.
“That would not set our product apart from others in the market. What we need is something totally different that creates a new category once again, just like we did before with the gel mattress.”
What the sales side wanted was a new type of mattress similar to none—something that would offer a completely different concept of sleep.
What is Body Pressure Dispersion?
Lying on a mattress puts pressure on muscles at the buttocks and elsewhere. The comfort in bed depends on how well the pressure is dispersed over the body.
What is the key factor that determines the comfort of sleep and has to be considered in designing a new mattress........
The team members thought over and over. Turnover dynamics during sleep was the answer they found.
To pursue “a mattress that reduces the number of rollovers by providing sleep comfort, while better supporting the body when needing to change position.”
Sleep proceeds in 90-minute cycles of deep sleep and light sleep. We roll over in bed in-between deep sleep and light sleep, usually several times a night. Movement while we are asleep is a protective mechanism to ensure stable sleep patterns.
This can be thought as a necessary rollover.
When you sleep on a hard floor, you probably roll over frequently, trying to disperse the high pressure being applied to the parts in contact with the floor, as a protection against blood flow blocking.
This type of rollover consumes muscle power and hinders sleep, therefore, the less, the better.
Sleep comfort with a reduced number of unneeded rollovers while assisting necessary rollovers—that was what the project team decided to focus on for the best possible quality of sleep.
We had conducted biometrics that the Lifestyle Health Sciences Research Center (LHSRC) of Aisin had through joint research with academic professionals during the development of the gel mattress. The team members thought they could develop new products with a rollover property.
“This will work and outperform low rebound urethane mattresses.”
The project entered into the phase of developing a new product.
Two target properties for the material to be created were set: "comfort" and "easy rollover" during sleep. For the first one, the team already had expertise in body pressure dispersion through the gel mattress.
The real challenge was the latter.
Conventional gel mattresses and competing low rebound mattresses are form-fitting, but the property can be a disadvantage for rollover movements.
In other words, the comfort of sleep and easy rollover are properties contradictory to each other.
Nonetheless, the project members were determined to create a cushion material that would provide both, i.e., body pressure dispersion as good as that of a gel mattress and flexibility that would support rolling movements in sleep.
“Low rebound mattresses have a drawback. They tend to become harder in winter.
Our new product should provide the same level of softness all year around. That would what differentiate it from others.”
Easier said than done.
“You want something that offers desirable flexibility and softness. And, at the same time, the properties have to be kept at the same level regardless of seasons. That's a tall order.”
That was the response from the Material Engineering Dept.
In addition, mattresses require good heat resistance, taking into account the high temperatures they are exposed to during transport.
And, above all, they must be light and cost competitive.
What was needed was a dream material that would clear all the difficulties.
The difference between mattress materials
Left: Hard materials, e.g., tatami mats, have poor cushioning but facilitate body movements.
Right: Soft materials, e.g., sponge, have good cushioning but make body movements difficult.
A material called elastomer was picked as the most promising.
Elastomer properties include rubber-like resilience and flexibility. When heated, it is as easily processable as plastics.
The team took the idea to a leading chemical manufacturer that produced styrene elastomer, but received was a short, cold reply.
“What you are asking is something impossible. A material that is heat-resistant and flexible in a bed size volume? We would very much like to know how to make that one.”
The project seemed technically stalled, but every cloud has a silver lining. Company T, an automotive rubber/urethane molded parts and service supplier, offered collaborative development.
It was the only company that said, “All right. We’ll give it our best shot.”
More than a year passed without any tangible results.
In July 2001, a merciless notification arrived.
“We don't have time to spend on this project anymore. The team is disbanded.”
It was a done deal.
What Is an Elastomer?
A natural or synthetic polymer compound having elastic properties, e.g., rubber.