Restricting short-wavelength light in the evening to improve sleep in recreational athletes – A pilot study

Figures & data

Table I. Sleep hygiene practices.

	No-light restriction			Light restriction			Results of statistical analysis
	M	SD	%	M	SD	%	Df	t	p
Daytime naps lasting two or more hours, or past 3 PM	.07	.21	6.90	.08	.18	8.33	14	.231	.820
Went to bed 30 min earlier or later than yesterday	.33	.35	32.76	.30	.33	30.00	14	−.280	.784
Got-up 30 min earlier or later than yesterday	.25	.35	24.14	.30	.24	30.00	14	.459	.654
Exercised within the last hour before bedtime	.12	.28	12.07	.08	.22	8.33	14	−.619	.546
Used alcohol, tobacco, caffeine within the last four hours before bedtime	.28	.34	30.77	.23	.35	23.33	14	−.676	.510
Did something that may wake me up before bedtime	.66	.26	65.52	.60	.41	60.00	14	−.603	.556
Went to bed feeling stressed, angry, upset, or nervous	.10	.21	10.34	.15	.23	15.00	14	.899	.384
Use my bed for things other than sleeping or sex	.41	.41	39.66	.47	.38	46.67	14	.577	.573
I did important work before bedtime	.18	.29	18.87	.05	.10	5.00	14	−1.586	.135
I thought, planned, or worried when I was in bed	.02	.06	1.72	.13	.28	13.33	14	1.974	.068
Slept at home	.98	.15	98.28	.92	.15	91.67	14	−1.262	.228
Had a bed or room partner	.04	.10	3.45	.08	.18	8.33	14	.953	.357

Note. The answer format of all questions was Yes (1) or No (0). Statistics are based on mean values rather than percentages. The percentages indicate how often a behaviour occurred across all nights within each condition.

Table II. Descriptive statistics and results of the statistical testing for actigraphy-based and diary-based sleep estimates (self-report).

	No-light restriction		Light restriction		Results of statistical analysis
	M	SD	M	SD	Df2	F	p	η2p
Actigraphy-based
Lights-off (hh:min)	00:03	01:02	23:57	00:54	13	.358	.560	.027
Lights-on (hh:min)	08:11	00:37	8:12	00:49	13	.003	.956	.000
SOL (hh:min)	00:11	00:12	00:06	00:03	13	1.117	.310	.079
WASO (hh:min)	00:45	00:18	00:47	00:17	13	.139	.715	.011
Fragmentation (%)	27.89	9.21	28.65	8.36	13	.255	.622	.019
TST (hh:min)	07:10	01:02	07:17	00:38	13	.608	.450	.045
SE (%)	85.58	5.76	85.57	5.12	13	.000	.998	.000
Diary based (self-report)
Lights-off	23:55	00:55	23:46	00:45	14	1.022	.329	.068
Lights-on	08:09	00:32	08:14	00:40	14	.242	.630	.017
SOL (hh:min)	00:19	00:11	00:12	00:07	12	11.607	.005	.492
WASO (hh:min)	00:13	00:09	00:11	00:08	9	.564	.472	.059
Awakenings (#)	1.74	.67	1.23	.42	9	3.482	.095	.279
TST (hh:min)	07:30	00:36	07:49	00:40	13	2.740	.122	.174
Sleep Quality
Sleep Quality (1–10)	6.91	1.02	7.48	.76	14	6.106	.027	.304
Refreshed (1–10)	6.43	1.25	6.94	1.14	14	4.45	.053	.241
KSS evening (1–9)	6.40	1.03	5.95	1.15	14	2.878	.112	.171
KSS morning (1–9)	4.23	1.32	3.62	1.02	14	4.634	.049	.249