Pillow use: The behaviour of cervical pain, sleep quality and pillow comfort in side sleepers
From: Man Ther. 2009 May 6. [Epub ahead of print]
Pillow performance research has largely involved testing pillows of novel shape and design, comparing contour and noncontour shaped pillows and comparing contour pillows with the participants’ usual pillow. Shields et al. who undertook a systematic review regarding the effect of contour or cervical pillow use on neck pain, highlighted the methodological flaws in these studies and concluded that there was insufficient evidence to support the use of contour pillows in the management of chronic neck pain. Helewa et al. reported that contour pillows were ineffective in the management of chronic neck pain unless combined with active neck exercises.
The paucity of research has caused health professionals to provide patient advice regarding neck pillows based on the anecdotal suggestions of expert colleagues and professional associations. This advice has included the use of malleable pillows, a cervical roll, a contour pillow or a down or urethane pillow. Furthermore the range of marketing advice provided by pillow manufacturers is confusing for consumers, although details regarding this statement by the authors was not substantiated by evidence.
This paper reports the performance of commonly used type of pillows from specific manufacturers and their association with neck pain behavior. This pillow field trial was undertaken to:
usual pillow and the trial pillows.
Pillows used in this study were a polyester, synthetic fibre fill pillow, foam regular shape and foam contour shape pillows. It was stated that both foam pillows were molded from high density foam, although other details regarding the pillows were left to the reader to investigate via manufacturer name and website address. Details regarding manufacturer and website address were provided for all pillows used. Also provided was a latex rubber pillow and feather pillows which were purchased by the principal author.
The pillows varied in length from 70 to 73 cm and in width from 45 to 46 cm. The depth of the foam regular pillow was 120 mm (4.7 in), the foam contour pillow varied between 120 (4.7) and 142 mm (5.5 in) across the contour, the latex pillow was 115 mm (4.5 in), the feather pillow was 120 mm (4.7 in) and the polyester pillow was 118 mm (4.6). The study was conducted independently of any additional involvement of pillow manufacturers. Compression was not noted, however, one migh assume that a high density foam pillow has less compressibility than latex, therefore, one cannot be sure as to the properties of the foam pillows contributing to poor results. It should be noted that the latex pillow would be mid-range in compression between the high density foam pillows and the high compression of the feather pillow.
This study provides the first reports that pillow type can be recommended by health practitioners to alter the behaviour of neck pain for self reported side sleepers. It provides the basis for further investigation of pillow performance with specific groups of people (with known musculoskeletal problems or other sleeping positions) and a basis for evidence-based prescription of pillows for individuals suffering from regular waking pain, reduced pillow comfort or sleep quality.
The authors state, “The study findings are in direct conflict with historically held anecdotal advice regarding pillow selection in the management of cervico-thoracic symptoms.” This, in my opinion is not substantiated by the evidence presented. It is not known why pillows shown to decrease symptoms and improve sleep quality indicated in previous studies were not considered. Studies regarding water based pillows were not included in the references.
Subjects’ own pillow performed similarly to the polyester and foam pillows in terms of production of waking symptoms and maintenance of retiring pain. The authors state, “The shape of the foam pillow appeared to make no difference to waking pain or abolition of night pain. However the contour pillow was less comfortable and provided poorer quality sleep. Thus the contour pillow is less efficacious for these reasons.” This may have been the case for the particular contour pillow used, however, the conclusion cannot be generalized to all contour pillows as parameters like Density (lbs / ft3), Percent of Indent Force Deflection, Tear Strength (lbs/lin inch) and Elongation Pecentage vary considerably and greatly effect pillow performance. Contour shaped foam pillows were initially developed to support the cervical lordosis in the supine sleep position. Hence further investigation of the association between contour pillow shape and symptom behaviour in supine sleepers is indicated. Moreover, contour pillows of different heights require examination with respect to subject anthropometry, symptom behaviour, sleep quality and pillow comfort ratings.
The feather pillow was a consistent poor performer in all outcome measures and therefore cannot be recommended as an alternative should subjects request a pillow which is better than their own. However the rubber pillow performed consistently well, and was a better performer than subjects’ own pillow in all outcome measures and should be recommended as an alternative should subjects seek a better performing pillow than their own. Again, specific qualities are not mentioned, however, manufacturer and website address are detailed. Like other studies, the relationship to the manufacturer must be suspect. Future studies should refrain from noting specific manufacturers and should address specific features of the materials as stated previous for the foam pillows.
The authors note, seven days appears to be a suitable period for a pillow trial as all drop-outs occurred before the fifth trial day. The ‘washout period’ of own pillow use for seven days between pillow trials also appeared to be appropriate to reduce trial pillow symptoms, to catch up on sleep from poor quality sleep from the trial pillows and to retain the interest of the study sample.
The authors further state, “The fit of pillow-to-human form has not been reported in the literature, and was not investigated in this study. Anthropometric studies may thus provide useful information regarding if, and what, anatomical parameters will ensure a comfortable, symptom free union between person, mattress and pillow.” The authors should be aware of studies like, Prediction of Optimal Pillow Height by Anthropometric Parameters, Pei-Te Huang, Alice M.K., in IFMBE Proceedings 15, pp. 222-223, 2007, where an actual formula based on anthropometrics is presented.
The authors note several limitations in this study including an inability to completely blind subjects for pillow type, reliance on daily self-report measures of pain occurrence and duration, sleep quality and pillow comfort, and a lack of information on subjects’ own pillows. There was a surprisingly high number of waking pain reports on subjects’ own pillows, questioning our assumption that these were the most comfortable pillows ever used by subjects. Although there was no difference in subject reports of known reasons for waking pain between the trial pillows, there was a noticeably high percentage on subjects’ own pillows in the first trial week. This could lead to questions such as ‘Did this occur because subjects were anxious about the trial, or perhaps more aware of waking pain?’ If this is so, it must be considered that reports of cervical waking pain on the trial pillows may well have been related to known reasons other than the pillow, but were perhaps ascribed to the pillow itself, in error. The potential for over and under reporting of symptoms during the trial pillow weeks must be considered.
For reasons stated, these types of studies are very difficult and the authors should be praised for their efforts. The authors conclude, “This study provides evidence to support recommendation of rubber pillows in the management of
waking cervical pain, and to improve sleep quality and pillow comfort.” It should be noted that the only conclusion that can be reached is that the specific rubber pillow performed better in the parameters studied than the specific foam and specific contour pillow used in the study, and that the specific feather pillow was least effective for unspecified or evaluated neck pain. To use a specific pillow and assume all pilllows made of the base material are the same is not warranted. To note the manufacturer name and website address brings into question the reasons for choosing specific pillows, relationships among manufacturer to study participants, and these studies are additionally noted to be used by the specific manufacturer as marketing materials.
