Longitudinal study of self-awakening and sleep/wake habits in adolescents

Figures & data

Figure 1 Sleep/wake habits in each group for 5 years.Abbreviations: CFA, consistently forced-awakened group; CSA, consistently self-awakened group; ME, morningness–eveningness; MIX, mixed group.

Table 1 Main effects and interactions of group and year for sleep/wake habit, subjective sleep estimation, and daytime symptoms

	Group			Year				Interaction
	F	df	P	F	df	ɛ	P	F	df	P
Bedtime
Week day	7.15	2, 359	<0.01	7.44	4, 1436	0.870	<0.001	0.54	8, 1436	NS
Week end	3.94	2, 358	<0.05	3.55	4, 1432	0.876	<0.05	1.46	8, 1432	NS
Wake-up time
Week day	7.23	2, 357	<0.01	5.63	4, 1428	0.832	<0.001	0.62	8, 1428	NS
Week end	2.31	2, 356	NS	1.23	4, 1424	0.917	NS	1.20	8, 1424	NS
Sleep time
Week day	8.06	2, 353	<0.001	9.77	4, 1412	0.923	<0.001	0.86	8, 1412	NS
Week end	0.73	2, 352	NS	1.85	4, 1408	0.922	NS	0.39	8, 1408	NS
Morningness score	5.69	2, 106	<0.01	3.00	4, 424	0.937	<0.05	1.66	8, 424	NS
Subjective sleep estimation
Sleep latency	0.80	2, 349	NS	0.91	4, 1396	0.863	NS	1.67	8, 1396	NS
Sleep depth	3.30	2, 349	<0.05	0.97	4, 1396	0.968	NS	0.98	8, 1396	NS
Number of awakenings	9.24	2, 353	<0.001	0.84	4, 1412	0.941	NS	0.23	8, 1412	NS
Bed out latency	1.33	2, 349	NS	1.64	4, 1396	0.878	NS	0.69	8, 1396	NS
Comfort after awakening	3.37	2, 357	<0.05	1.78	4, 1428	0.986	NS	0.89	8, 1428	NS
Daytime symptoms
Nap	0.72	2, 349	NS	0.44	4, 1396	0.965	NS	1.72	8, 1396	<0.10
Doze off	4.61	2, 336	<0.05	2.95	4, 1344	0.968	<0.05	0.81	8, 1344	NS
Sleepiness	2.06	2, 335	NS	1.19	4, 1340	0.960	NS	0.91	8, 1340	NS

Abbreviations: df, degrees of freedom; NS, not significant.

Table 2 Parameters of the sleep/wake habit, subjective sleep estimation, and daytime symptoms in each group

	CSA group	MIX group	CFA group
Bedtime (hours)
Week day	23.39 (0.19)^a	24.11 (0.07)^b	24.15 (0.06)^b
Week end	23.91 (0.25)^a	24.62 (0.08)^b	24.61 (0.07)^b
Wake-up time (hours)
Week day	6.40 (0.16)^a	6.91 (0.06)^b	6.69 (0.05)^a
Week end	8.23 (0.30)	8.73 (0.10)	8.86 (0.09)
Sleep time (hours)
Week day	6.83 (0.18)^a	6.63 (0.06)^a	6.34 (0.05)^b
Week end	8.12 (0.33)	7.94 (0.11)	8.10 (0.09)
Morningness score	52.60 (3.09)	50.08 (0.87)^a	46.39 (0.83)^b
Subjective sleep estimation
Sleep latency (minutes)	19.32 (3.37)	17.06 (1.10)	15.75 (0.93)
Sleep depth†1	2.44 (0.19)	2.14 (0.07)	1.99 (0.06)
Number of awakenings	0.66 (0.12)^a	0.32 (0.04)^b	0.18 (0.03)^c
Bed out latency (minutes)	3.91 (1.26)	6.07 (0.43)	5.75 (0.36)
Comfort after awakening†2	3.58 (0.22)^a	3.08 (0.08)	2.99 (0.06)^b
Number of daytime symptoms†3
Nap	0.77 (0.19)	0.60 (0.07)	0.69 (0.06)
Doze off	1.88 (0.37)^a	2.36 (0.13)^a	2.77 (0.11)^b
Sleepiness	3.65 (0.42)	3.86 (0.15)	4.20 (0.12)

Notes: Values in parentheses represent standard deviation; there is a significant difference (P < 0.05) between “a,” “b,” and “c;”

†1 response scale: 1 deep, 5 light;

†2 response scale: 1 very bad, 5 very good;

†3 number per week.

Abbreviations: CFA, consistently forced-awakened group; CSA, consistently self-awakened group; MIX, mixed group.

Figure 2 Subjective sleep quality and subjective ratings after awakening for 5 years.Notes:^†1response scale: 1 deep, 5 light; ^†2response scale: 1 very bad, 5 very good; ^†3number per week.Abbreviations: CFA, consistently forced-awakened group; CSA, consistently self-awakened group; MIX, mixed group.

Table 3 Parameters of the sleep/wake habit, subjective sleep estimation, and daytime symptoms for 5 years

	First year	Second year	Third year	Fourth year	Fifth year
Bedtime (hours)
Week day	23.59 (0.12)^a	23.70 (0.09)^a	23.88 (0.13)	24.06 (0.10)^b	24.20 (0.10)^b
Week end	24.19 (0.11)	24.19 (0.12)^a	24.40 (0.14)	24.48 (0.12)	24.62 (0.14)^b
Wake-up time (hours)
Week day	6.51 (0.06)^a	6.71 (0.07)^b	6.71 (0.07)^b	6.68 (0.07)^b	6.73 (0.08)^b
Week end	8.53 (0.16)	8.83 (0.15)	8.48 (0.20)	8.49 (0.16)	8.71 (0.16)
Sleep time (hours)
Week day	6.82 (0.08)^a	6.76 (0.08)^a	6.65 (0.09)^a	6.65 (0.10)	6.26 (0.11)^b
Week end	8.20 (0.20)	8.34 (0.20)	7.90 (0.18)	7.97 (0.17)	7.85 (0.17)
Morningness score	46.93 (1.30)^a	50.89 (1.47)^b	50.55 (1.41)	50.09 (1.38)	49.99 (1.32)
Subjective sleep estimation
Sleep latency (minutes)	16.76 (1.35)	16.17 (1.69)	18.40 (1.57)	17.02 (1.37)	18.52 (1.79)
Sleep depth†1	2.23 (0.10)	2.27 (0.10)	2.13 (0.09)	2.20 (0.10)	2.10 (0.09)
Number of awakenings	0.38 (0.06)	0.44 (0.08)	0.42 (0.07)	0.38 (0.06)	0.31 (0.06)
Bed out latency (minutes)	5.08 (0.69)	4.77 (0.59)	4.44 (0.53)	5.75 (0.68)	6.19 (0.86)
Comfort after awakening†2	2.90 (0.11)	2.90 (0.11)	2.69 (0.11)	2.72 (0.10)	2.71 (0.11)
Number of daytime symptoms†3
Nap	0.59 (0.10)	0.75 (0.09)	0.64 (0.12)	0.72 (0.12)	0.72 (0.13)
Doze off	2.00 (0.20)^a	2.43 (0.20)	2.43 (0.20)	2.69 (0.19)^b	2.13 (0.19)
Sleepiness	3.98 (0.22)	4.13 (0.23)	3.98 (0.23)	3.85 (0.22)	3.59 (0.23)

Notes: Values in parentheses represent standard deviation; there is a significant difference (P < 0.05) between “a” and “b;”

†1 response scale: 1 deep, 5 light;

†2 response scale: 1 very bad, 5 very good;

†3 number per week.