Researchers say a lack of sleep affects the function of genes related to stress and cell renewal, possibly contributing to poor health.Doctors know that being chronically sleep-deprived can be hazardous to your health. Night-shift workers, college crammers and all the rest of us who get less than our fair share of zzz's are more likely to be obese and to suffer cardiovascular woes than people who get a consistent, healthful eight hours.