In 1900, L.E. Wilson, from Nebraska, filed a patent for a “Shoulder brace and antisnoring attachment” [26]. The device consisted of a metal “prodding device”, kept in place by adjustable, washable and ventilated straps. Not only did the device block the patient from adopting the supine position, the device also forced the patient to roll over to a lateral position. The first patent for a device for medical application was filed by T. Thomas in 1907: “A belt and shield to be worn at night to give support to the wearer, prevent his sleeping on his back, to prevent dreaming and snoring…” [27].

In 1908, two patents were filed, both titled “Antisnoring device” by C.F. Rohwer and L.F. Liebhardt. These devices aimed to “provide a simple and easily applied device, which will effectively prevent snoring, sleep talking, bad dreams and other disagreeable features with which many persons contend when sleeping on their backs”, by securing a hollow ball composed of compressible material, such as rubber on the wearer’s back [28, 29].

E.R. Boots invented a new sleeping garment, for which a patent was filed in 1941 [30]. This garment consisted of a pocket sewn onto the back panel of a nightshirt or pyjama, sized to retain a so-called “anti-snore medium such as a sponge rubber ball”. This ball served as an obstacle for the wearer to sleep in supine position.

Under a decade later, the journal CHEST published a letter written by a patient’s wife [31]. She had cured her husband’s sleep apnea snoring problem by “having sewn a pocket into the back of a T-shirt and having inserted a hollow, lightweight plastic ball, to prevent her husband sleeping on his back”. To our best knowledge, this is the first publication of “positional therapy” in medical literature.

It was not until the mid-1980s that the first scientific studies on positional therapy were published.

Kavey published the results of two patients who had been instructed to attach a ball in a sock to the back of their nightshirt in such a way as to make the supine position uncomfortable [32]. Henceforth, variations of the tennis ball techniques have been described in the literature varying from vests, “shark fins” or special pillows, as shown in Table 1. After running a thorough search strategy in the MEDLINE and Embase databases, 24 relevant articles were found. Seven studies were excluded from the overview. Two studies did not provide information on the effect of PT on OSA parameters and were omitted from the overview. Five studies evaluated the effect on OSA of an array of devices resulting in an elevated posture and head extension. As these devices did not prevent the patient from assuming the supine position, the studies were not included in the overview. All studies report positive effect of positional therapy on the AHI [24–33, 40, 43, 44, 48, 49, 55, 56, 58].