1. Division of Oral Function and Rehabilitation, Department of Oral Health Science, Nihon University School of Dentistry at Matsudo, Matsudo, Chiba 271 – 8587, Japan
2. Japan Somnology Center, Institute of europsychiatry, Shibuya, Tokyo 151 – 0053, Japan
3. Department of Internal Medicine, Nihon University School of Dentistry at Matsudo, Matsudo, Chiba 271 – 8587, Japan
4. Sleep Research Group, Charles Perkins Centre, University of Sydney, Sydney 2006, Australia
5. Sydney School of Health Sciences, Faculty of edicine and Health, University of Sydney, Sydney 2006, Australia