The periodic deformations of planar nematic (1), planar twisted nematic (2), and hybrid aligned nematic (3) layers, were analyzed numerically. In the cases (1) and (2), the periodic deformations induced by magnetic field under strong anchoring conditions, were taken into account. In the case (3), the so called splay stripes, which arise spontaneously under the weak anchoring conditions, were considered. In each of these geometries, two different types of periodic deformations were found. For all deformations, the director distributions were calculated. The ranges of material and layer parameters, for which the periodic deformations occurred, were determined. The following features, common for most of the deformations, were found: (1) wide regions with nearly homogeneous deformation exist in two halves of a stripe in strongly deformed layers; (2) the spatial period of the deformations diverges to infinity with variation of suitable parameter (e.g. field strength, twist angle, anchoring energy etc.); (3) above critical values of parameters, the nearly homogeneous regions spread over the whole layer and the periodic deformations are replaced by homogeneous distortions.