Sleep duration and subjective psychological well-being in adolescence: a longitudinal study in Switzerland and Norway

Figures & data

Table 1 Description of sleep duration and subjective psychological well-being, separated by: CH and N; age groups (I, 10–11 year olds; II, 12–13 year olds; III, 14–15 year olds); and the three measurement time points (T1, T2, and T3)

Age	Country	T1		T2		T3		Between T1 and T2		Between T2 and T3		Over T1 and T3
		M (min)	SD	M (min)	SD	M (min)	SD	t (df)	P/d	t (df)	P/d	t (df)	P/d
Sleep duration
I	CH	600	38	591	45	574	39	2.82 (211)	0.005/0.22	8.81 (248)	0.000/0.41	8.66 (201)	0.000/0.68
	N	589	45	583	44	571	37	3.05 (281)	0.003/0.13	6.37 (283)	0.000/0.31	8.20 (284)	0.000/0.45
II	CH	563	43	551	45	537	65	4.96 (360)	0.000/0.25	8.36 (440)	0.000/0.25	6.41 (370)	0.000/0.45
	N	550	48	541	44	522	51	4.58 (368)	0.000/0.19	8.70 (321)	0.000/0.39	12.01 (331)	0.000/0.56
III	CH	518	43	516	42	502	42	3.83 (364)	0.001/0.04	7.82 (375)	0.000/0.35	9.47 (359)	0.000/0.38
	N	502	51	497	50	481	52	2.51 (191)	0.013/0.10	5.01 (171)	0.000/0.33	5.23 (175)	0.000/0.42
		F(2; 2,178)=534.64; P<0.001		F(2; 2,072)=439.69; P<0.001		F(2; 2,024)=347.36; P<0.001
Subjective psychological well-being
I	CH	3.40	0.44	3.35	0.46	3.34	0.45	1.22 (212)	0.23/0.11	0.02 (256)	0.99/0.03	2.08 (215)	0.04/0.15
	N	3.44	0.43	3.35	0.47	3.27	0.50	3.22 (295)	0.00/0.20	3.78 (296)	0.00/0.17	6.21 (296)	0.00/0.36
II	CH	3.31	0.49	3.28	0.48	3.24	0.52	1.22 (363)	0.22/0.06	2.02 (457)	0.04/0.07	2.60 (378)	0.01/0.13
	N	3.29	0.48	3.20	0.51	3.09	0.52	4.64 (383)	0.00/0.18	5.60 (335)	0.00/0.20	8.19 (342)	0.00/0.39
III	CH	3.23	0.48	3.25	0.53	3.22	0.56	1.05 (371)	0.30/0.05	1.14 (386)	0.26/0.05	0.16 (366)	0.87/0.01
	N	3.19	0.48	3.12	0.54	3.06	0.54	1.49 (193)	0.14/0.13	0.57 (173)	0.57/0.11	2.50 (175)	0.01/0.25
		F(2; 2,198)=32.47; P<0.001		F(2; 2,103)=13.73; P<0.001		F(2; 2,066)=12.43; P<0.001

Notes: Cohen’s d=0.2–0.49, little effect; d=0.5–0.79, middle effect; d>0.8, large effect. Subjective psychological well-being was measured with the Bern well-being questionnaire for adolescents (BFW/J)-subscales: “Positive attitude towards life” and “Joy in life”. Rating scales with higher mean values reflect greater psychological well-being.

Abbreviations: M, mean; SD, standard deviation; CH, Switzerland; N, Norway; T1, baseline in May; T2, November (6 months after T1); T3, (12 months after T1, again in May); I, mean age, 11.2 years; II, mean age, 13.0 years; III, mean age, 14.9 years; min, minutes.

Table 2 Correlations between sleep duration and subjective psychological well-being, separated by the three age groups (I, 10–11 year olds; II, 12–13 year olds; III, 14–15 year olds) and three measurement time points (T1, T2, and T3)

SPW		Cronbach’s alpha	Sleep duration
			T1	T2	T3
I	T1	0.73	0.05	0.07	0.04
	T2	0.78	0.12**	0.11*	0.09*
	T3	0.82	0.11*	0.10*	0.10*
II	T1	0.78	0.14**	0.09*	0.10**
	T2	0.80	0.12**	0.14**	0.08*
	T3	0.82	0.12**	0.09**	0.12**
III	T1	0.79	0.20**	0.10*	0.10*
	T2	0.85	0.19**	0.13**	0.16**
	T3	0.84	0.12**	0.09*	0.06

Notes:

* P<0.05.

** P<0.01. Higher means reflect a more positive SPW.

Abbreviations: T1, baseline in May; T2, in November (6 months after T1); T3, May (12 months after T1); I, mean age, 11.2 years; II, mean age, 13.0 years; III, mean age, 14.9 years; SPW, subjective psychological well-being.

Figure 1 Longitudinal path model.

Notes: Standardized estimates are displayed. Bold letters indicate that this path is significantly different for the respective age group. Fit indices for the displayed model set all paths equal across age groups, except for the path between sleep duration at T2 and sleep duration at T3 for the oldest age group: χ²=28.01; df=23; P=0.215; RMSEA =0.007. Model comparison of the displayed model with the model setting all paths equal across age groups: χ²=23.35; df=1: P<0.001. ^#P=0.08; *P<0.05; **P<0.01; ***P<0.001.
Abbreviations: RMSEA, root mean square error of approximation; I, 10–11 year olds; II, 12–13 year olds; III, 14–15 year olds; e, error term.