In this study, a composite day extension of the Hocking (2005) analysis technique was used to study diurnal and seasonal variations in atmospheric short-period (less than 2 h) gravity waves (GWs) in the mesosphere and lower thermosphere (MLT). Observations were made using meteor radar wind data collected in Langfang, China (39.4° N, 116.7° E). GW activity was found to be strong over a 24-hour period, above the 95% confidence level, during almost every month of the year, as determined by an analysis of the corresponding power spectra. A 12-hour period of particularly high activity was also evident in April and October for zonal wind variance, as well as in January, April, May, and December for meridional wind variance. Additional periods were observed for the first time, including 4-, 6-, and 8-hour cycles with confidence intervals greater than 95%. This suggests the possibility that GW activity could be modulated by solar-heating tidal wave harmonics. The zonal and meridional wind variances also exhibited annual, semi-annual, and quasi-4-month oscillation periods. Lastly, weak quasi-3-month and strong quasi-2.4-month cycles were observed at specific altitudes.