Table 4.

Number of transitions and fragmentation index in sham-operated experimental controls and in rats with traumatic brain injury (TBI) during the lights-on and lights-off periods. A 24-h sleep EEG epoch was recorded on the 7th post-TBI month.

Parameter	Lights-On		Lights-Off		TOTAL
	Sham	TBI	Sham	TBI	Sham	TBI
	(n = 11)	(n = 14)	(n = 11)	(n = 14)	(n = 11)	(n = 14)
Number of transitions from a deeper to a lighter sleep stage
N2–Awake	4.09 ± 1.49	6.42 ± 1.82	5.54 ± 2.06	6.00 ± 1.20	9.63 ± 3.22	12.43 ± 2.76
N3–Awake	10.54 ± 1.60	8.07 ± 1.43	8.72 ± 1.09	10.50 ± 1.23	19.27 ± 2.38	18.57 ± 2.34
REM–Awake	11.91 ± 2.09	13.14 ± 1.33	10.09 ± 0.79	11.29 ± 0.74	22.00 ± 2.17	24.43 ± 1.36
N3–N2	9.27 ± 2.05	11.57 ± 2.85	5.81 ± 1.82	7.92 ± 1.64	15.09 ± 3.52	19.50 ± 4.17
REM–N2	13.18 ± 3.36	14.93 ± 3.33	4.91 ± 1.19	6.71 ± 1.54	18.09 ± 4.52	21.64 ± 4.71
REM–N3	47.64 ± 4.49	47.43 ± 6.51	32.55 ± 3.27	28.14 ± 4.21	80.18 ± 7.35	75.57 ± 10.22
Total	96.63 ± 4.35	101.57 ± 3.54	67.64 ± 4.36	70.57 ± 2.71	164.27 ± 7.94	172.14 ± 4.50
Deep-to-light sleep fragmentation index	8.01 ± 0.37	8.39 ± 0.35	5.73 ± 0.37	5.88 ± 0.22	6.83 ± 0.33	7.14 ± 0.21
Number of transitions to
Awake	21.73 ± 3.07	26.50 ± 2.91	24.36 ± 1.98	28.36 ± 2.29	46.09 ± 4.30	54.86 ± 4.37
N2	29.82 ± 5.47	42.29 ± 6.73	26.18 ± 5.31	33.00 ± 5.09	56.00 ± 10.42	75.29 ± 10.91
N3	73.45 ± 2.66	86.50 ± 4.14 *	62.27 ± 3.65	63.29 ± 2.51	135.73 ± 5.53	149.79 ± 4.72
REM	59.73 ± 3.28	70.93 ± 4.72 *	48.55 ± 3.39	46.07 ± 3.56	108.27 ± 5.58	117.00 ± 7.19
Total	184.73 ± 9.88	226.21 ± 10.91 *	161.40 ± 10.72	170.71 ± 7.83	346.09 ± 18.39	396.93 ± 13.70 *
Fragmentation index	15.31 ± 0.81	18.67 ± 0.94 *	13.47 ± 0.89	14.23 ± 0.65	14.40 ± 0.94	16.46 ± 0.59 *

Data are shown as the mean ± standard deviation of the mean. Statistical significance: * p < 0.05 compared with the sham group (Mann–Whitney U test). Abbreviations: N2, N2 sleep stage; N3, N3 sleep stage; REM, rapid eye movement sleep; TBI, traumatic brain injury; W, awake.