Tidal winds are the strongest global scale motions in the upper mesosphere. In addition to their dynamical interactions, they play a significant role in the transport of trace species. The downward transport of atomic oxygen affects the absorption of sunlight because of its impact on ozone concentrations and also affects the conversion of absorbed energy to heat through exothermic reactions. Tides provide a mechanism to move some of the energy absorbed during molecular oxygen photolysis downward into the middle atmosphere. Model calculations indicate that tides result in global net heating by solar energy that is stronger by about 35% near 85 km. A simultaneous decrease in net heating occurs above the mesopause. This is one of several mechanisms by which tidal variability can affect the mean state of the mesosphere.