Background: Sleep accounts for approximately one-third of a person’s lifetime. It is a relaxing activity that relieves mental and physical fatigue. Pillows of different sizes, shapes, and materials have been designed to improve sleep quality by achieving an optimal sleep posture. Objects: This study aimed to determine which pillow provides the most comfortable and supports the head and neck during sleep, which may enhance sleep quality. Methods: Twenty-eight healthy adults (19 males and 9 females) with an average age of 29 years participated in this cross-sectional study. This experiment was conducted while the participants laid down for 5 minutes in four different pillow conditions: (1) no pillow (NP), (2) neck support foam pillow (NSFP), (3) standard microfiber filled pillow (SFP), and (4) hybrid foam pillow (HFP). The head-neck peak pressure, cranio-vertebral angle in supine (CVAs), cranio-horizontal angle in supine (CHAs), chin-sternum distance (CSD), and muscle tone of sternocleidomastoid were analyzed using one-way repeated measures analysis of variance (ANOVA). The significance level was set at p < 0.05. Results: The head-neck peak pressure was the highest in the NSFP condition, followed by the NP, SFP, and HFP conditions. The CVAs, CHAs, and CSD of the SFP were lower than those of the other pillows. Muscle tone was the highest in the NP condition, followed by the of NSFP, HFP, and SFP conditions. The participants subjective comfort level in both the supine and side-lying postures was highest in the HFP condition, followed by the SFP and NSFP conditions. Conclusion: This study can be used to establish the importance of pillow selection for highquality sleep. The results of this study, suggest that a hybrid pillow with a good supportive core and appropriate fluffiness can maintain comfort and correct cervical spine alignment during sleep.

INTRODUCTION
MATERIALS AND METHODS
    1. Subjects
    2. Procedure
    3. Pillow Types
    4. Outcome Measures
    5. Statistical Analysis
RESULTS
    1. Pressure Under the Head and Neck
    2. Head and Neck Alignment
    3. Muscle Tone of the SCM
    4. Level of Subjective Comfort
DISCUSSION
CONCLUSIONS
REFERENCES

• Kyeong-Ah Moon(Department of Physical Therapy, The Graduate School, Yonsei University)
• Ji-Hyun Kim(Department of Physical Therapy, The Graduate School, Yonsei University)
• Ye Jin Kim(Department of Physical Therapy, The Graduate School, Yonsei University)
• Joo-Hee Park(Department of Physical Therapy, The Graduate School, Yonsei University, Department of Physical Therapy, College of Health Sciences, Yonsei University, Wonju, Korea)
• Hye-Seon Jeon(Department of Physical Therapy, The Graduate School, Yonsei University, Department of Physical Therapy, College of Health Sciences, Yonsei University, Wonju, Korea) Corresponding author