Research Conducted at Duke University
During 1998 and 1999, research regarding the effect of mattress design on sleep was conducted for Select Comfort by Dr. Gail Marsh and Dr. William Wohlgemuth of the Duke University Medical Center Sleep Disorders Center. This research involved a clinical study of possible differences in the quality of sleep experienced by 30 subjects who were in good health, but whose sleep quality may have deteriorated due to excessive nighttime awakenings or age. The sleep surfaces tested were Sleep Number® beds and the subjects’ own innerspring mattresses.
The study subjects each slept on their own innerspring mattress for a week, and then on a Sleep Number bed for a week. Both subjective and objective measurement criteria were used to compare the sleep quality provided by the two types of sleep surfaces. The study subjects subjectively evaluated their quality of sleep by completing detailed sleep diaries regarding their sleep experiences on the two sleep surfaces. The objective assessments employed by the researchers included measurement of body movements, polysomonographic measurement of a number of sleep variables to assess sleep quality and architecture, and physical testing. The specific sleep factors objectively measured included body movement, sleep onset time, several types of wakefulness after sleep onset, average time spent in bed, average time in bed spent asleep, sleep efficiency, levels of stress hormones (hormones that tend to make it harder to sleep) and level of melatonin (a hormone that tends to enhance sleep).
Although statistically significant differences did not result from all of these various inquiries, many of the measurements taken did yield such significant results. With respect to the subjective measurements, study subjects reported statistically significant results reflecting a better quality of sleep, less time spent awake in bed, and waking up feeling less fatigued and more rested in the morning after sleeping on the Sleep Number beds. Turning to the results of the objective measurements, the only statistically significant finding was that the study subjects spent an average of about 15 minutes less time in bed when sleeping on the Sleep Number bed than when sleeping on their own innerspring mattress. This objective finding is especially meaningful given the above-noted subjective reports by the subjects that they felt less fatigued and more rested after such a shorter period of sleep. It appears that Sleep Number beds provided the study subjects with a more efficient sleep experience. While the research conducted at Duke University didn’t find statistically significant results relative to all of the areas explored, it did indicate that there are some important benefits of sleeping on a Sleep Number bed. Most importantly, the researchers concluded that:
While the research conducted at Duke University didn’t find statistically significant results relative to all of the areas explored, it did indicate that there are some important benefits of sleeping on a Sleep Number bed.
Most importantly, the researchers concluded that:
“[T]he subjective measures of sleep showed several results that favored sleeping on the [Sleep Number®] mattress over sleeping on their own. Subjective measures are invaluable as a means of knowing how a person experienced their sleep. The results from the sleep diaries were clear cut in demonstrating a superiority of the sleeping experience on the [Sleep Number] mattress. Sleep quality was rated better and the feeling of restedness was rated higher after a night of sleep on the [Sleep Number] mattress as compared to sleeping on the person’s own mattress.”