Persistent tiredness usually comes down to one of a few fixable problems: poor sleep quality, a nutritional gap, dehydration, or an underlying medical condition that hasn’t been caught yet. What you should take depends on which of those is driving your fatigue. Here’s a practical breakdown of the supplements, nutrients, and other options that have real evidence behind them.
Rule Out a Medical Cause First
Before spending money on supplements, it’s worth knowing that tiredness is one of the most common symptoms of an underactive thyroid. Subclinical hypothyroidism, where thyroid function is just slightly off, often goes undetected because the only noticeable symptom is feeling drained. A simple blood test can check your TSH level; anything above 4.5 mIU per liter is considered elevated. Iron deficiency anemia, vitamin D deficiency, and blood sugar problems are other frequent culprits. A basic blood panel can rule out all of these in one visit, and if one of them is the cause, no supplement will work as well as treating the actual problem.
Magnesium
Magnesium is involved in over 300 enzyme reactions in your body, including the ones that convert food into usable energy. Roughly half of adults don’t get enough from their diet alone, and low magnesium commonly shows up as fatigue, muscle cramps, and poor sleep. If you’re only going to try one supplement for tiredness, this is a reasonable place to start.
Not all forms are equal, though. Magnesium malate is the form most associated with energy support and is easy on the stomach. Magnesium glycinate is better suited for sleep and stress, since it has a calming effect. Magnesium oxide, the cheapest option on most shelves, is poorly absorbed and mainly useful as a laxative. Citrate absorbs well but can cause loose stools at higher doses. For general fatigue, magnesium malate or glycinate are the best picks.
CoQ10
Every cell in your body contains a compound called CoQ10, which plays a central role in converting fats and carbohydrates into ATP, the molecule your cells actually use for energy. Your natural CoQ10 levels decline with age, and certain medications (particularly statins) can lower them further. Supplement doses typically range from 30 to 100 mg per day, which is significantly more than you’d get from food alone. CoQ10 won’t produce a caffeine-like jolt, but people with low levels often notice a gradual improvement in overall energy over several weeks.
Ashwagandha
Ashwagandha is one of the better-studied herbal options for fatigue, particularly when tiredness is linked to stress. In a clinical trial of 120 adults experiencing low energy and fatigue, those who took ashwagandha root extract twice daily for 12 weeks showed measurable reductions in fatigue compared to placebo. Benefits in studies tend to be more pronounced at doses of 500 to 600 mg per day of a standardized root extract. Lower doses (around 200 to 300 mg) have also shown effects, but the results are less consistent. Look for products standardized to contain a specific percentage of withanolides, the active compounds, since unstandardized products vary wildly in potency.
Hydration and Electrolytes
Mild dehydration is one of the most overlooked causes of tiredness, and it doesn’t take much. Losing just 1 to 2 percent of your body’s water content can cause fatigue, difficulty concentrating, and headaches. Plain water works for most situations, but if you’re sweating heavily, eating very little, or recovering from illness, your electrolyte balance matters too. Sodium, potassium, and magnesium all need to be in the right range for your muscles and nerves to function properly. When any of these drop too low, fatigue is one of the first symptoms.
You don’t necessarily need a branded electrolyte drink. An oral rehydration solution made with water, a small amount of salt, and sugar works well. If you suspect electrolytes are part of the issue, pay attention to whether your fatigue worsens after exercise, in hot weather, or on days when you eat less than usual.
Caffeine: Helpful Within Limits
Caffeine is the most widely used stimulant on earth, and it works. It blocks the receptor in your brain that makes you feel sleepy, providing a genuine boost to alertness. The FDA considers up to 400 mg per day safe for most adults, which translates to roughly two to three 12-ounce cups of coffee. Problems start when people use caffeine to mask a deeper issue. If you need more than 400 mg just to get through a normal day, that’s a signal something else is going on, not a sign you need more caffeine.
Timing matters as much as quantity. Caffeine has a half-life of about five to six hours, meaning half of what you drank at 2 p.m. is still active in your system at 7 or 8 p.m. Afternoon caffeine is one of the most common reasons people sleep poorly and then feel exhausted the next morning, creating a cycle that more caffeine only worsens.
Melatonin for Sleep-Related Fatigue
If your tiredness stems from poor or mistimed sleep rather than a nutritional gap, melatonin can help reset your internal clock. It’s not a sedative in the traditional sense. It signals to your brain that it’s time for sleep, which makes it most useful when your sleep schedule has drifted (from jet lag, shift work, or late-night screen habits). The NHS recommends 3 mg taken at bedtime as a standard dose, with the option to increase to 6 mg if needed. Taking it too early in the evening or at excessively high doses can cause grogginess the next day, which defeats the purpose.
For most people, melatonin works best as a short-term tool to re-establish a consistent bedtime rather than something you take indefinitely. Once your sleep pattern is stable, the fatigue that comes from poor sleep quality often resolves on its own.
B Vitamins
B vitamins, especially B12 and folate, are essential for red blood cell production and energy metabolism. A deficiency in either one causes fatigue that no amount of sleep will fix. Vegans and vegetarians are at higher risk for B12 deficiency since it’s found almost exclusively in animal products. People over 50 absorb less B12 from food regardless of diet. If your levels are normal, taking extra B vitamins won’t give you more energy; they’re not a stimulant. But if you’re low, correcting the deficiency can make a dramatic difference within a few weeks.
What to Try and In What Order
Start with the basics: sleep quality, hydration, and a blood test to check for deficiencies or thyroid issues. These account for the majority of unexplained fatigue. If those come back normal, magnesium malate and CoQ10 are low-risk options with reasonable evidence behind them. Add ashwagandha if stress is a major factor in your tiredness. Use caffeine strategically rather than reflexively, and consider melatonin only if your sleep schedule is genuinely off track. Stacking five supplements at once makes it impossible to tell what’s actually working, so introduce one at a time and give each a few weeks before judging the results.