Table 2. PSQI-J component scores by quintiles of rice, bread, and noodle intake as well as dietary glycemic index and glycemic load.

	Q1 (lowest)			Q2			Q3 (middle)			Q4			Q5 (highest)			P valuea
Rice
Sleep duration (hours)	6.2	±	0.9	6.3	±	0.8	6.4	±	0.8	6.4	±	0.9	6.4	±	0.8	0.008
PSQI-J
Subjective sleep quality	1.26	±	0.69	1.16	±	0.64	1.18	±	0.68	1.15	±	0.64	1.08	±	0.63	0.063
Sleep latency	0.72	±	0.77	0.70	±	0.74	0.70	±	0.77	0.67	±	0.74	0.67	±	0.75	0.630
Sleep duration	1.04	±	0.84	0.91	±	0.74	0.81	±	0.70	0.84	±	0.75	0.79	±	0.73	0.003
Habitual sleep efficiency	0.13	±	0.50	0.06	±	0.25	0.07	±	0.31	0.08	±	0.34	0.09	±	0.40	0.787
Sleep disturbances	0.93	±	0.51	0.94	±	0.51	0.90	±	0.50	0.89	±	0.49	0.86	±	0.51	0.290
Use of sleep medication	0.08	±	0.40	0.04	±	0.26	0.05	±	0.33	0.06	±	0.36	0.03	±	0.29	0.773
Daytime dysfunction	0.99	±	0.73	0.91	±	0.67	0.87	±	0.74	0.96	±	0.72	0.86	±	0.71	0.211
Bread
Sleep duration (hours)	6.4	±	0.8	6.4	±	0.8	6.3	±	0.8	6.3	±	0.8	6.2	±	0.8	0.007
PSQI-J
Subjective sleep quality	1.13	±	0.69	1.17	±	0.60	1.14	±	0.64	1.17	±	0.65	1.22	±	0.69	0.407
Sleep latency	0.71	±	0.76	0.71	±	0.75	0.64	±	0.73	0.69	±	0.73	0.72	±	0.78	0.570
Sleep duration	0.77	±	0.75	0.83	±	0.74	0.90	±	0.74	0.92	±	0.78	0.97	±	0.78	0.003
Habitual sleep efficiency	0.07	±	0.30	0.10	±	0.39	0.10	±	0.37	0.09	±	0.41	0.08	±	0.37	0.706
Sleep disturbances	0.88	±	0.50	0.94	±	0.52	0.93	±	0.50	0.89	±	0.50	0.90	±	0.51	0.383
Use of sleep medication	0.05	±	0.33	0.05	±	0.32	0.05	±	0.33	0.04	±	0.29	0.06	±	0.38	0.905
Daytime dysfunction	0.89	±	0.72	0.94	±	0.71	0.97	±	0.73	0.91	±	0.71	0.89	±	0.69	0.491
Noodles
Sleep duration (hours)	6.38	±	0.83	6.32	±	0.81	6.37	±	0.80	6.30	±	0.86	6.27	±	0.82	0.275
PSQI-J
Subjective sleep quality	1.11	±	0.66	1.14	±	0.66	1.13	±	0.63	1.22	±	0.68	1.23	±	0.65	0.021
Sleep latency	0.64	±	0.72	0.65	±	0.70	0.67	±	0.75	0.72	±	0.79	0.79	±	0.78	0.049
Sleep duration	0.82	±	0.75	0.91	±	0.76	0.82	±	0.73	0.90	±	0.77	0.94	±	0.78	0.114
Habitual sleep efficiency	0.05	±	0.28	0.07	±	0.37	0.10	±	0.39	0.09	±	0.39	0.12	±	0.40	0.069
Sleep disturbances	0.81	±	0.52	0.94	±	0.51	0.87	±	0.50	0.95	±	0.49	0.96	±	0.50	<0.001
Use of sleep medication	0.02	±	0.23	0.03	±	0.27	0.03	±	0.28	0.06	±	0.36	0.10	±	0.46	0.008
Daytime dysfunction	0.83	±	0.72	0.91	±	0.70	0.92	±	0.72	0.90	±	0.71	1.03	±	0.70	0.005
Dietary GI
Sleep duration (hours)	6.3	±	0.8	6.3	±	0.8	6.3	±	0.8	6.4	±	0.8	6.4	±	0.8	0.025
PSQI-J
Subjective sleep quality	1.21	±	0.68	1.17	±	0.62	1.16	±	0.65	1.17	±	0.70	1.11	±	0.63	0.279
Sleep latency	0.73	±	0.76	0.74	±	0.76	0.64	±	0.76	0.66	±	0.74	0.69	±	0.72	0.382
Sleep duration	0.98	±	0.78	0.91	±	0.78	0.88	±	0.74	0.84	±	0.76	0.79	±	0.73	0.013
Habitual sleep efficiency	0.09	±	0.38	0.10	±	0.42	0.09	±	0.36	0.08	±	0.34	0.07	±	0.36	0.923
Sleep disturbances	0.93	±	0.51	0.94	±	0.50	0.88	±	0.51	0.91	±	0.50	0.87	±	0.50	0.204
Use of sleep medication	0.06	±	0.32	0.09	±	0.45	0.03	±	0.29	0.05	±	0.35	0.02	±	0.21	0.065
Daytime dysfunction	0.96	±	0.71	0.91	±	0.71	0.88	±	0.71	0.94	±	0.72	0.89	±	0.71	0.561
Dietary GL
Sleep duration (hours)	6.3	±	0.8	6.3	±	0.8	6.3	±	0.8	6.4	±	0.8	6.4	±	0.8	0.067
PSQI-J
Subjective sleep quality	1.15	±	0.66	1.19	±	0.66	1.13	±	0.62	1.15	±	0.64	1.20	±	0.71	0.515
Sleep latency	0.71	±	0.75	0.76	±	0.77	0.62	±	0.74	0.67	±	0.73	0.71	±	0.77	0.159
Sleep duration	0.94	±	0.81	0.91	±	0.74	0.87	±	0.72	0.82	±	0.76	0.85	±	0.77	0.241
Habitual sleep efficiency	0.12	±	0.46	0.09	±	0.39	0.07	±	0.34	0.09	±	0.35	0.07	±	0.30	0.370
Sleep disturbances	0.87	±	0.50	0.92	±	0.48	0.86	±	0.52	0.96	±	0.48	0.91	±	0.53	0.041
Use of sleep medication	0.04	±	0.33	0.07	±	0.37	0.05	±	0.32	0.06	±	0.40	0.02	±	0.20	0.388
Daytime dysfunction	0.94	±	0.72	0.88	±	0.70	0.89	±	0.71	0.92	±	0.71	0.96	±	0.73	0.537

PSQI-J, the Japanese version of the Pittsburgh Sleep Quality Index; GI, glycemic index; GL, glycemic load; Q: quintile.

^aLinear regression analyses were used to assess the linear trends between sleep duration and each PSQI-J component score across the quintiles of starchy food intake, dietary GI, and dietary GL by using the median value of each quintile.