A total of 5747 workers (mean age: 43.8) were investigated to clarify the current state regarding insomnia and hypertension. Workers with hypertension were more likely to suffer from insomnia than those without hypertension, and workers with insomnia showed a significantly higher incidence of hypertension than those without insomnia, which suggested that insomnia and hypertension have a close relationship with each other. In addition, based on the results of this investigation, the following were clarified: many workers with insomnia do not spontaneously consult a physician, nor do they have interviews with a physician regarding sleep. They often remain untreated, or depend on nightcaps and/or over-the-counter drugs according to their judgment, without receiving appropriate treatment with hypnotics. Diet and exercise therapies are important in the treatment of hypertension, but it is suggested that sleep therapy facilitating sufficient sleep is equally effective, and hypertension can be treated directly and indirectly through such therapy.