Table 1.

Characteristics of the baseline population.

	Number (%)
Characteristics	Females (n = 1640)	Males (n = 1931)	Total (n = 3571)
Personal characteristics
Whether the student were only-children
Yes	597 (36.40)	850 (44.02)	1447 (40.52)
No	1043 (63.60)	1081 (55.98)	2124 (59.48)
Time spent outdoors hours/week
<7	459 (27.99)	535 (27.71)	994 (27.84)
7–14	540 (32.93)	542 (28.07)	1082 (30.30)
≥14	641 (39.09)	854 (44.23)	1495 (41.87)
Time in meditation hours/week
<28	601 (36.65)	455 (23.56)	1056 (29.57)
28–56	550 (33.54)	917 (47.49)	1467 (41.08)
≥56	489 (29.82)	559 (28.95)	1048 (29.35)
Sleep duration (hours/day)
<7	110 (6.71)	154 (7.98)	264 (7.39)
7–9	961 (58.60)	1034 (53.55)	1995 (55.87)
≥9	569 (34.70)	743 (38.48)	1312 (36.74)
BMI
Non-overweight/obesity	1533 (93.48)	1568 (81.20)	3101 (86.84)
Overweight/obesity	107 (6.52)	363 (18.8)	470 (13.16)
Self-reported health status
Very good	641 (39.09)	806 (41.74)	1447 (40.52)
Better	590 (35.98)	677 (35.06)	1267 (35.48)
Average	356 (21.71)	376 (19.47)	732 (20.50)
Not so good	53 (3.23)	72 (3.73)	125 (3.50)
Family characteristics
Nationality
Han	1490 (90.85)	1775 (91.92)	3265 (91.43)
Minority	150 (9.15)	156 (8.08)	306 (8.57)
The type of area in which the family lived
City/county center	479 (29.21)	529 (27.40)	1008 (28.23)
City/county fringe	178 (10.85)	243 (12.58)	421 (11.79)
City/county urban-rural junction	102 (6.22)	124 (6.42)	226 (6.33)
Towns outside the city/county	87 (5.30)	134 (6.94)	221 (6.19)
Countryside	767 (46.77)	877 (45.42)	1644 (46.04)
Others	27 (1.65)	24 (1.24)	51 (1.43)
Whether students lived with their parents
Living with both	1082 (65.98)	1249 (64.68)	2331 (65.28)
Living with one party	307 (18.72)	386 (19.99)	693 (19.41)
Not living with either party	251 (15.30)	296 (15.33)	547 (15.32)
Family economic conditions
Richer	72 (4.39)	121 (6.27)	193 (5.40)
Medium	1181 (72.01)	1331 (68.93)	2512 (70.34)
Very difficult	387 (23.60)	479 (24.81)	866 (24.25)