Several studies show ashwagandha to be effective with mild fatigue, at the very least.
Rhodiola rosea is shown in some studies to be effective and in some studies to not be effective. It’s inconclusive.
B vitamins, vitamin C, zinc, iron, and magnesium all play important roles in energy. You can either target one or get a good multi-vitamin. It’s extremely difficult to find a good multi-vitamin. Unfortunately, they all look the same if you don’t know what you’re looking for. The truth is, if you search “multivitamins” on Amazon, 99% of them are mediocre at best, including the top-selling popular ones. They just don’t have the proper amount of vitamins. They rip you off. I don’t get money for saying this, but here are two fantastic options, two needles from the haystack. Both are perfect for improving energy levels. Here’s one and here’s the other. If you’re interested in taking individual vitamins, I’ve linked the proper dosages. Almost every supplement ever sold has been at a less than optimal dose.
Creatine has been shown to fight mental fatigue.
It works for me. I’ve been using it for years. It’s especially effective when you’re sleep-deprived. It’s on many other lists on this blog because it improves mood as well. Its an amino acid. Feel free to take higher than the recommended dosage. You can safely go up to at least 3x or 4x that. This is a supplement where you can’t really be deceived by the companies selling them. You can get pretty much any you see on Amazon. I tried linking to the best value, but I could be wrong.