Table 3.

Confusion matrix of the Firstbeat method and polysomnography sleep stage epoch comparisons.

Firstbeat (N)	Polysomnography (N)
	Light	SWSa	REMb	Wake	Total
Light	12,737c	2189	3445	492	18,863
SWS	2683	5867c	40	96	8686
REM	2072	131	5576c	205	7984
Wake	1435	125	355	2598c	4513
Total	18,927	8312	9416	3391	40,046c
Correct stage classification (%)	67.3	70.6	59.2	76.6	N/Ad

^aSWS: slow wave sleep.

^bREM: rapid eye movement.

^cDiagonals indicate the number of correctly categorized epochs in the respective sleep stage.

^dN/A: not applicable.