2. You keep poor sleep patterns
Sleepiness is not the same as fatigue (which is a general lack of energy), but one of the most common causes of feeling tired is simply not sleeping enough. In addition to too little shut-eye, keeping irregular sleeping patterns and even sleeping too much can also make you feel tired. To get back on the right track, try to get into a routine of sleeping at consistent times—while only getting as much sleep as you really need—and you’ll be surprised how much better you will feel.