Before using smartphones

After starting to use smartphones

P value

Time spent using smartphones before sleeping

<30 min

117

(45.0)

52

(20.0)

<0.001

30 min - 1 hr

78

(30.0)

95

(36.5)

1 - 2 hrs

35

(13.5)

76

(29.2)

2 - 4 hrs

11

(4.2)

31

(11.9)

5 hrs

2

(0.8)

4

(1.5)

missing

17

(6.5)

2

(0.8)

Bedtime

before 22 o’clock

8

(3.1)

2

(0.8)

<0.001

22 - 24 o’clock

139

(53.5)

70

(26.9)

24 - 2 o’clock

106

(40.8)

174

(66.9)

after 2 o’clock

2

(0.8)

14

(5.4)

missing

5

(1.9)

0

(0.0)

Sleeping hours

<5 hrs

14

(5.4)

32

(12.3)

<0.001

5 - 6 hrs

89

(34.2)

127

(48.8)

6 - 7 hrs

108

(41.5)

86

(33.1)

7 - 8 hrs

40

(15.4)

13

(5.0)

>8 hrs

3

(1.2)

1

(0.4)

missing

6

(2.3)

1

(0.4)

Feeling of sufficient sleep

yes

127

(48.8)

82

(31.5)

<0.001

no

56

(21.5)

98

(37.7)

neither

68

(26.2)

75

(28.8)

missing

9

(3.5)

5

(1.9)

Refreshing feeling after waking up

yes

86

(33.1)

57

(21.9)

0.008

no

97

(37.3)

126

(48.5)

neither

65

(25.0)

68

(26.2)

missing

12

(4.6)

9

(3.5)

Wake-up time on a weekday

5 - 6 o’clock

22

(8.5)

24

(9.2)

0.031

6 - 7 o’clock

172

(66.2)

142

(54.6)

7 - 8 o’clock

57

(21.9)

85

(32.7)

after 8 o’clock

4

(1.5)

6

(2.3)

missing

5

(1.9)

3

(1.2)

Wake-up time on a holiday

5 - 7 o’clock

9

(3.5)

12

(4.6)

ns

7 - 9 o’clock

114

(43.8)

108

(41.5)

9 - 11 o’clock

109

(41.9)

112

(43.1)

after 11 o’clock

23

(8.8)

25

(9.6)

missing

5

(1.9)

3

(1.2)