For many adventuring parties being knocked unconscious is a penalty only if you actually miss your turn. There are so many healing abilities that spending more than a round at 0 hp is often a long-forgotten memory after 4th or 5th level when healing word and revivify become de rigueur choices for your bard, druid, cleric, and celestial soul sorcerer. 

This can keep combat quick and smooth, but also has the disappointing effect, noted at gaming tables worldwide, of making combat a kind of nothing event in most cases. If there's no consequence beyond using a 2nd-level spell slot for being reduced to 0 hp, why try to avoid it? 

The answer in this case is to reintroduce consequences for reaching 0 hp without crippling a character. There are several ways to do this, three of which are presented here.