The effects of positive nitrogen pressure (0psi to 10psi above ambient) on the reflection spectrum of holographic polymer dispersed liquid crystal (H-PDLC) Bragg gratings has been experimentally analyzed showing shifts in Bragg wavelength and peak broadening effects. We have observed a spectral blue-shift in the peak reflection wavelength that occurs with increasing pressure. Using statistical analysis techniques, we have shown that this is a real effect that can be quantified. The spectral dependence on applied pressure is explained by mechanical deformations to the polymer network, which is assumed to behave linearly. These devices have potential usage as optical pressure sensors.