(a) Effect of α-pinene and zolpidem on sleep stage: NREMS, REMS and wake. α-pinene and zolpidem increased the amount of NREMS and wave stages. This enhancement was fully inhibited by flumazenil. (b) Effect of α-pinene and zolpidem on delta activity. α-pinene did not change the delta activity. Yang et al., 2014, Mol. Pharm.