By Day and by Night

A Mexican science fiction film where the over-population problem has been solved by programming people to operate in either day or night, and not both. A Mexican science fiction film where the over-population problem has been solved by programming people to operate in either day or night, and not both. A Mexican science fiction film where the over-population problem has been solved by programming people to operate in either day or night, and not both. A Mexican science fiction film where the over-population problem has been solved by programming people to operate in either day or night, and not both.