When you are dieting to lose unwanted body fat, the period of caloric restriction should not be more than 6 to 10 weeks (obviously less if you reach your goals sooner).
If you have not managed to reach your target weight, take a break for 2-3 weeks at caloric maintenance and then start again.
The longer you stay in a caloric deficit the harder it will be to lose fat and more prone to have unwanted negative side effects.
This side effects will negatively impact your sleep, sex life, daily mood, and just overall well-being. This is because your body will make metabolic adaptations during a chronic state of caloric deficit to increase its chances of survival.