A header-based power gating structure inserts PMOS as sleep transistors between the power rail and the circuit. Since PMOS sleep transistors in the functional mode are turned-on continuously, Negative Bias Temperature Instability (NBTI) influences the lifetime reliability of PMOS sleep transistors seriously. To tolerate NBTI effect, sizes of PMOS sleep transistors are normally over-sized. In this paper, we propose a novel NBTI-aware power gating architecture to extend the lifetime of PMOS sleep transistors. In our structure, sleep transistors are switched on/off periodically so that overall turned-on times of sleep transistors are reduced and sleep transistors are less influenced by NBTI effect. The experimental results show that our approach can achieve better lifetime extensions of PMOS sleep transistors than previous works and few area overheads.