The word seiza is written with two Chinese characters; “sei” meaning “correct, proper, true” (and by itself can be pronounced tadashii, meaning “just right” or “appropriate”) and “za” meaning “sitting posture” (written with an ideograph that looks like people sitting on a raised floor under a roof).
Many people complain that seiza makes their feet “go to sleep” (known in Japan as “shibireru”) but this tends to be from lack of proper exercise, weak leg muscles and poor circulation; not necessarily due to the position of sitting in seiza. If one is sitting correctly, one should be able to perform seiza for anything up to an hour a day without discomfort.
Proper seiza, helps to naturally align your body and spinal column, focusses on your “centre” and leads to an alert mind and body – hence its common use in meditation.
Different schools of martial arts may have slightly different versions of seiza, but for a rough guideline, sit in seiza as follows: