An oral appliance for treating snoring and/or sleep apnea of a subject, comprising a hard plastic dental tray, a transpalatal bar extending between the left lingual side of the dental tray and the right lingual side of the dental tray, and a tongue restrainer having at least two spaced-apart wires extending from the posterior side of the transpalatal bar and a hard plastic tongue-contacting portion attached at the distal end of the wires. The tongue-contacting portion has smooth edges, a rounded posterior end, and a width between its right side and left side greater than the space between the wires, providing greater comfort and user safety, while the wires provide flexibility to vertically position the tongue restrainer and mechanical strength to maintain the tongue restrainer in place once positioned.
