In spite of being considered silent most genes called absent are expressed in a daily changing pattern of elevated (red) and lowered expression level (green) over the 48h period of alternating light and darkness (bottom), consistent with circadian pattern in highly expressed genes. The plot shows four phase groups (roman numbers) in four murine tissues (data from [10] and [12]). On each pane expression profiles are stacked in order of autocorrelation with 24h lag (Ac, vertical axis).