Visually, sideways bends appear to be halfway between forward and backward bends, and their effects reflect that blend: they offer some of the stretching, opening action of forward bends  as well as some of the activating, energizing effect of backward bends.

:• Stretch, open, and energize the spine.

• Open the breathing, and thereby the flow of life force.

• Increase awareness of the spinal energies.

As with all bending poses, the spine tends to bend in the regions where it is most flexible, which can overstretch the lateral spinal muscles on one side of the body. It also closes off the breath in the lung on the other side, which impedes the flow of prana in the spine. Therefore at all times during the sideways bend, keep the spine long and active, distribute the sideways bend throughout the entire length of the spine, and maintain openness in the underside of the rib cage.

The spine is not in its natural curves during a sideways bend. It should appear to have its natural curves when viewed from the side. This requires some vigilance, many students forward or, more commonly, backward when bending to the side. This is particularly common in chandrasana, in which tight shoulders can cause you to lean forward or backward.

Also, the structure of the facet joints in the spine dictates that any sideways bend of the spine causes some twist in the spine (and vice versa). You can minimize this by keeping the spine as long as possible during the sideways bend, so that the facet joints force as little twisting as possible.

Overall, the upper body should feel as though it is pressed between two panes of glass during a sideways bend. And if it's a standing sideways bend, such as chandrasana, the entire body should feel as though it is pressed between two panes of glass. In any case, spread the sideways bend uniformly throughout the spine, including the neck.

If you come into a sideways bend on an inhalation, it will help you keep the spine longer. On the ensuing exhalation, maintain that length and relax into the pose.  While holding the pose, use each inhalation to lengthen your spine, and on each exhalation relax a bit more. Exit the pose on an inhalation if you're exiting against the force of gravity, which is the case for most sideways bends; otherwise, exit on an exhalation.