As reionization is inherently coupled with galaxies —the dominant sources of ionizing photons— understanding galaxy evolution in the early universe relies on understanding the process of reionization. Lyman-alpha emission has played a pivotal role in constraining the neutral hydrogen (HI) fraction of the intergalactic medium (IGM) during the epoch of reionization (EoR) thanks to the resonant nature of Lyman-alpha scattering with HI. A spectroscopic dataset of galaxies in the early universe, obtained by the DEIMOS (optical) and MOSFIRE (near-infrared; NIR) spectrographs on the Keck telescopes, is utilized for investigating the evolution of the IGM during EoR by measuring the Lyman-alpha equivalent width (EW) distribution. I will present the results of the spectroscopic analysis, including our IGM HI fraction measurement and the discovery of a highly ionized region at z ~ 7.6, which highlights the inhomogeneity of reionization. I will also discuss future directions for improving the use of Lyman-alpha as a probe of reionization.