Background: Neck and back pain are the most common reported musculoskeletal disorders. Applying surface electromyography to determine muscular activity has been used for a long time for clinical diagnosis. OBJECTIVE: The aim of this study was to assess the effect of two sleeping postures (recommended and preferred postures) on neck muscles activities and fatigue by measuring cervical muscles activities using electromyography. In the recommended posture (Model 1), the cervical and lumbar spine are horizontally aligned, while in the preferred posture (Model 2), the cervical spine is not aligned with lumbar spine. Methods: A total of nine healthy male subjects were asked to side rest with a pillow with adjustable height. The electromyography examinations were performed for upper trapezius (UT) and sternocleidomastoid (SCM) muscles of participants. After acquiring the anthropometric data, participants laid on mattress with medium hardness at the two postures for 30 minutes. Results: Comparison between the two models showed a significant difference ( ) in the level of electrical activity of neck muscles. In addition, a remarkable difference ( ) was observed in terms of neck muscle fatigue between the two tested models. Conclusions: The results indicate that the recommended posture developed and tested in this study would reduce the level of fatigue and activity of neck muscles during resting.