Tired during the day = too little sleep.

Are you eating to satisfy hunger? If not, try eating until you're satisfied.

When I went low carb, my sleep normalized for the first time in a LONG time. My theory is that the reduction in insulin somehow made me more sensitive to melatonin.

But stress will mess with your sleep. Too few calories. Even too few carbs. Too much exercise. Other stressors? Reduce whatever stress you can. Maybe try taking a break from exercise for a while if the sleep/tired issue continues.

Low sodium gives you more of a "blah" sort of fatigue in my experience.

Sleepiness is your body telling you that you need more sleep.

Carbs used to give me that feeling. Now exercise does. Or simple lack of sufficient sleep.