Table 1.

Statistical modelling results. Shown are results of likelihood ratio tests for both the main models and models comparing caffeine experiments, along with associated sample counts (n₁, n₂), P-values and the results of pairwise comparisons. Effects of LPS were tested by comparing models with and without the group-by-epoch interaction (or group itself for cytokine data) using likelihood ratio tests. Caffeine experiments were fit in separate models together with equivalent saline controls; since there are only two factor levels no pairwise comparisons are needed. Post hoc comparisons used the Kenward-Roger method and P-values for pairwise comparisons were adjusted for multiple comparisons by estimating a multivariate t-distribution using the emmeans package for R.³⁶ IL-6, interleukin 6; LPS, lipopolysaccharide; MCP-1, monocyte chemoattractant protein-1; Movt, movement; PXM, piroxicam; SWA, slow wave activity; VEH, vehicle; wPLI, weighted phase lag index.

Measure		Likelihood ratio test/pairwise comparison	n1, n2	P-value	Measure		Likelihood ratio test/pairwise comparison	n1, n2	P-value
A	IL-6	χ2(4)=29.0		<0.0001	B	MCP-1	χ2(4)=29.1		<0.0001
		VEH vs low LPS	5, 18	0.68			VEH vs low LPS	5, 18	0.87
		VEH vs high LPS	5, 8	0.0004			VEH vs high LPS	5, 8	0.0003
		Low LPS vs high LPS	18, 8	0.0002			Low LPS vs high LPS	18, 8	<0.0001
		VEH vs PXM+low LPS	5, 12	0.23			VEH vs PXM+low LPS	5, 12	0.12
		Low LPS vs PXM+low LPS	18, 12	0.69			Low LPS vs PXM+low LPS	18, 12	0.17
		Low LPS vs aged low LPS	18, 13	0peak.0033			Low LPS vs aged low LPS	18, 13	0.014
C	SWA	χ2(4)=87.8		<0.0001	D	gamma	χ2(4)=78.6		<0.0001
		VEH vs low LPS	7, 17	<0.0001			VEH vs low LPS	7, 17	<0.0001
		VEH vs high LPS	7, 8	<0.0001			VEH vs high LPS	7, 8	<0.0001
		Low LPS vs high LPS	17, 8	0.041			Low LPS vs high LPS	17, 8	0.043
		VEH vs PXM+low LPS	7, 8	0.72			VEH vs PXM+low LPS	7, 8	0.5
		Low LPS vs PXM+low LPS	17, 8	<0.0001			Low LPS vs PXM+low LPS	17, 8	<0.0001
		Low LPS vs aged low LPS	17, 14	0.025			Low LPS vs aged low LPS	17, 14	0.36
Caffeine		χ2(1)=36.6	8, 10	<0.001	Caffeine		χ2(1)=61.5	8, 10	<0.0001
E	wPLI	χ2(4)=26.2		<0.0001	F	Movt	χ2(4)=18.8		0.00085
		VEH vs low LPS	7, 17	0.011			VEH vs low LPS	7, 17	0.014
		VEH vs high LPS	7, 8	0.002			VEH vs high LPS	7, 8	0.0005
		Low LPS vs high LPS	17, 8	0.61			Low LPS vs high LPS	17, 8	0.25
		VEH vs PXM+low LPS	7, 8	0.063			VEH vs PXM+low LPS	7, 8	0.23
		Low LPS vs PXM+low LPS	17, 8	1			Low LPS vs PXM+low LPS	17, 8	0.83
		Low LPS vs aged low LPS	17, 12	0.031			Low LPS vs aged low LPS	17, 14	0.99
Caffeine		χ2(1)=18.2	8, 10	0.0002	Caffeine		χ2(1)=18.8	8, 10	<0.0001
G	SWAMovt-matched	χ2(4)=21.5		0.00025	H	SWAQuiescent	χ2(4)=19.7		0.00057
		VEH vs low LPS	7, 16	0.0086			VEH vs low LPS	6, 16	0.67
		VEH vs high LPS	7, 5	0.0057			VEH vs high LPS	6, 5	0.32
		Low LPS vs high LPS	16, 5	0.77			Low LPS vs high LPS	16, 5	0.82
		VEH vs PXM+low LPS	7, 7	1			VEH vs PXM+low LPS	6, 7	1
		Low LPS vs PXM+low LPS	16, 7	0.013			Low LPS vs PXM+low LPS	16, 7	0.83
		Low LPS vs aged low LPS	16, 13	0.99			Low LPS vs aged low LPS	16, 13	0.0086
Caffeine		χ2(1)=3.98	8, 8	0.046	Caffeine		χ2(1)=2.61	8, 8	0.11
I	wPLIMovt-matched	χ2(4)=6.39		0.17	J	wPLIQuiescent	χ2(4)=4.77		0.31
Caffeine		χ2(1)=7.0	8, 6	0.0082	Caffeine		χ2(1)=1.49	8, 8	0.22