Methods for treating insomnia are disclosed. The methods are directed to administering a pharmaceutically effective amount of phosphodiesterase 5 (PDE5) inhibitor to a male individual suffering from insomnia. In addition, due to the PDE5 inhibitor positive effects on addressing erectile dysfunction (ED) in males, the present methods are directed to treating insomnia in patients that also suffer from ED by administering a pharmaceutically effective amount of a PDE5 inhibitor.