1 = very good
2 = good
3 = fair
4 = poor
5 = very poor

0 = no
1 = yes

1 = first-year university student
2 = second-year university student
3 = third-year university student
4 = fourth-year university student
5 = fifth-year university student
6 = postgraduate student

0 = female
1 = male

1 = city
2 = town
3 = countryside

1 = primary school and below
2 = junior high school
3 = high school or technical school
4 = bachelor
5 = postgraduate and above

afternoon nap
0 = 否
1 = 是

1 = morning-type
2 = M-type>evning-type
3 = intermediate-type
4 = E-type>M-type
5 = E-type

sleep duration
1 = 5 hours and below
2 = 6
3 = 7
4 = 8
5 = 9
6 = 10
7 = 11 hours and above

midnight snack habit
1 = yes
2 = no

smoke at least one cigarette per day for six months or longer
1 = No
2 = Yes, but I've quit.
3 = Yes,I still smoke

1 = No
2 = Yes，but I've quit
3 = Yes,I still drink