As a single writer, it would be easy for me to fall into that stereotypic trap of keeping irregular hours. Staying up all night as the creative urge takes hold; lounging in bed with a book until the sun hangs low in the west. One thing that keeps this from happening is the person in charge of my schedule: my cat, Samhain.
There is the morning and evening feeding schedule, of course, but it would be fairly simple to work around that. Samhain insists, however, that the rest of the schedule be maintained. I must not only get up at a certain time, but go to bed at the appointed time. Then there is yoga time, and play time, and time to brush teeth. I have to admit that I was the one who established the routine; Samhain only enforces it rigorously. (You try disobeying a Siamese cat.)
While I chafe sometimes under the tyranny, I have to admit that it keeps me from falling into sleep deprivation and other destructive habits. Pets have many ways of keeping us healthy. This article at Positive Health Wellness discusses a wide range of health benefits (for humans) of keeping a pet:
Just petting your animal helps to release the relaxation hormones. Your blood pressure will drop, and you are at a much lower risk of various side effects of too much stress..