Fig. 4.

Lithium shortens circadian period preferentially in cells from Li-R donors. a In Li-R subjects the period shortening effect of lithium inversely correlates with baseline period length. Li-R subjects with long (>25.8 h) periods show the greatest shortening effect of lithium. b In Li-NR subjects the relationship between baseline period length and the effect of lithium on period is attenuated and no longer significant. c) Li-R cells with long period (N = 18) show significant period shortening after lithium compared to Li-R cells with short period (N = 25). Lithium had no effect on period length in Li-NR with long (N = 11) or short (N = 4) period. * Indicates p < 0.05. d Representative rhythm traces of a Li-R cell with long period after treatment with vehicle or lithium 1 mM