Despite their limited resources, especially energy, wireless sensor networks (WSNs) are being accepted in many application areas. This makes them a challenging yet an appealing research area. Evidently, a lot of research work revolves around energy efficiency in order to prolong WSNs lifetime. A prominent amount of work suggests keeping radios of sensor nodes in low power sleep mode for most of the time. However, this duty-cycling results in increased network latency. Selection of an optimal duty-cycle is always challenging especially for applications where latency, along with energy consumption, plays an important role. This paper evaluates AREA-MAC for delay, energy, and packet delivery ratio factors for several duty-cycle values. AREA-MAC is a medium access control (MAC) protocol designed for realtime and energy-efficient WSN applications. Linear optimization is used to find the optimal value of duty-cycle in order to minimize delay and energy consumption and by keeping packet delivery ratio above a certain threshold.