Actually, in general men think about sex about as often as they do food or sleep. The median number of thoughts by this study showed about once per hour (18.6 times per day) as opposed to once every couple hours for women (9.9 times per day). So the myth that men think about sex constantly is really just a that; a myth. There are extremes on both ends for both men and women up to hundreds of thoughts per day or as low as 1 or less.

How Often Do Men and Women Think about Sex? | Psychology Today