Several widely available supplements can make you sleepy, each through a different mechanism. Melatonin, magnesium, L-theanine, valerian root, and a handful of others all promote drowsiness, but they vary considerably in how strong the effect is, how quickly it kicks in, and how solid the evidence behind them actually is. Here’s what each one does and what to expect.
Melatonin
Melatonin is the most popular sleep supplement for a reason: it mimics the hormone your brain already produces to signal that it’s time to sleep. Your body naturally ramps up melatonin production as evening light fades, and a supplement essentially pushes that signal earlier or makes it louder. It reaches peak levels in your blood about 1.3 to 1.5 hours after you take it, regardless of dose, so taking it 30 to 60 minutes before bed is standard advice, though some people benefit from taking it earlier in the evening.
Doses used in clinical trials range widely, from as low as 0.1 mg up to 10 mg. Many sleep researchers recommend starting at the low end (0.3 to 0.5 mg) because the goal is to nudge your body’s natural rhythm, not flood it. Higher doses don’t necessarily work better for falling asleep and can cause next-day grogginess.
One important note on long-term use: a large multinational study presented at the American Heart Association’s 2025 meeting found that people who took melatonin for at least one year had a higher rate of heart failure (5% vs. 3%) and roughly double the rate of all-cause mortality over five years compared to non-users. The researchers cautioned this doesn’t prove melatonin directly caused these outcomes, but it challenges the assumption that nightly melatonin use is completely harmless. If you’ve been taking it for months or years, it’s worth a conversation with your doctor.
Magnesium
Magnesium promotes sleepiness through several pathways at once. It enhances the activity of GABA, your brain’s main “calm down” chemical, by making GABA receptors more sensitive. It also blocks a type of brain signaling (called NMDA activity) that keeps neurons firing, and it helps lower cortisol, the stress hormone that can keep you wired at night. On top of that, it physically relaxes muscles, which is why people who carry tension in their shoulders or jaw often notice a difference.
Not all forms of magnesium are equal for sleep. Magnesium glycinate is the form most commonly recommended because it absorbs well (50 to 80% compared to less than 10% for cheaper forms like magnesium oxide) and is less likely to cause digestive issues. The glycine component is itself an inhibitory neurotransmitter that reinforces the calming effect. Clinical trials show benefits at 200 to 300 mg of elemental magnesium daily, with 240 mg taken 30 to 60 minutes before bed being a well-supported target dose.
L-Theanine
L-theanine is an amino acid found naturally in green tea. It doesn’t knock you out the way melatonin can. Instead, it shifts your brain into a more relaxed state by increasing alpha brain wave activity, the same pattern your brain produces during calm, wakeful relaxation or light meditation. A single 200 mg dose has been shown to significantly increase alpha wave power within three hours, with the effect measurable across the whole scalp.
This makes L-theanine particularly useful if racing thoughts are the thing keeping you awake. It takes the edge off mental alertness without causing heavy sedation, so you’re more likely to drift off naturally rather than feeling drugged. Many people combine it with magnesium for a stronger effect, and it’s also commonly stacked with a low dose of melatonin.
Valerian Root
Valerian root has centuries of traditional use as a sedative, but the clinical evidence is mixed. A meta-analysis of randomized controlled trials found that valerian was 1.8 times more likely than placebo to produce an improvement in sleep quality as a yes-or-no measure. However, when studies used more granular scales to rate sleep quality, five out of seven found no statistically significant benefit.
For falling asleep faster, results split down the middle: two studies found valerian reduced sleep onset by 14 to 17 minutes, while two others found no meaningful difference from placebo. Valerian seems to work better for some people than others, and it may take one to two weeks of consistent use before any effect becomes noticeable. It’s generally well tolerated, though some people report vivid dreams or mild headaches.
Tart Cherry Juice
Tart cherry juice is a less obvious sleep aid, but it contains natural melatonin along with compounds that reduce inflammation. In a pilot study on adults with insomnia, drinking tart cherry juice extended total sleep time by 84 minutes compared to placebo. A separate trial using tart cherry juice concentrate found a more modest increase of 34 minutes in total sleep time, along with a 5 to 6% improvement in sleep efficiency (the percentage of time in bed actually spent sleeping).
The practical downside is that you’re drinking a full glass of juice before bed, which means extra sugar and potentially a middle-of-the-night bathroom trip. Tart cherry extract capsules are available as an alternative, though they haven’t been studied as extensively as the juice itself.
Chamomile and Apigenin
Chamomile tea’s reputation as a bedtime drink comes largely from a compound called apigenin. Animal research has shown that apigenin activates GABA receptors in the brain, producing a mild sedative effect. Notably, this appears to work through a different binding site than prescription sleep medications like benzodiazepines, which may explain why chamomile feels gentler and doesn’t carry the same risk of dependence.
Concentrated apigenin supplements (typically 50 mg) have become popular in the biohacking community, largely driven by high-profile endorsements. The human evidence for isolated apigenin at these doses remains thin, though chamomile tea itself has shown modest improvements in sleep quality in a few small trials. It’s one of the lower-risk options to try, with the ritual of a warm drink before bed likely contributing to its effect.
GABA Supplements
GABA is the neurotransmitter that most sleep supplements are ultimately trying to boost, so taking it directly sounds logical. The reality is more complicated. GABA is a large molecule, and the scientific debate about whether it can cross from your bloodstream into your brain in meaningful amounts has continued for decades.
Current research suggests oral GABA may work through at least three routes: some portion may cross the blood-brain barrier directly, some acts on neurons in the gut, and some communicates with the brain indirectly through the vagus nerve. People who take GABA supplements (typical doses are 100 to 300 mg) often report feeling calmer within 30 to 60 minutes, though it’s difficult to separate this from placebo effects given the uncertainty about the mechanism.
5-HTP and Tryptophan
Both 5-HTP and tryptophan are precursors to serotonin, which your body then converts into melatonin. Taking either one can increase your natural melatonin production, making you sleepy in a more gradual, physiological way than taking melatonin directly. Tryptophan is the same amino acid in turkey that gets blamed (mostly unfairly) for post-Thanksgiving drowsiness. Typical supplement doses are 100 to 300 mg for 5-HTP and 500 mg to 1 g for tryptophan, taken about an hour before bed.
These carry a serious safety concern that other sleep supplements don’t. Because they raise serotonin levels, combining them with antidepressants (SSRIs or MAOIs) can trigger serotonin syndrome, a potentially life-threatening condition involving agitation, rapid heart rate, high blood pressure, and in severe cases, seizures. If you take any antidepressant, anti-migraine medication, or other serotonin-affecting drug, 5-HTP and tryptophan are off the table.
When and How to Take Them
Timing matters more than most people realize. Melatonin, magnesium glycinate, and 5-HTP all work best when taken 30 to 60 minutes before your target bedtime. L-theanine peaks in effect around three hours after ingestion, so some people prefer taking it earlier in the evening. If you’re using melatonin specifically to shift your sleep schedule earlier (say, after jet lag or a stretch of late nights), research on circadian rhythm shifting suggests taking it in the late afternoon, roughly 10 to 11 hours before your usual sleep midpoint, produces the largest time shift. In that case, use the lowest dose possible (0.5 mg) to avoid afternoon drowsiness.
Stacking multiple supplements is common, and certain combinations make physiological sense: magnesium plus L-theanine targets relaxation from two different angles without overlapping mechanisms. Adding a low dose of melatonin to that combination gives you a direct sleep-onset signal on top of the calming baseline. What you want to avoid is combining multiple supplements that all raise serotonin (5-HTP, tryptophan, and St. John’s Wort, for example), as the risks compound even without a prescription medication in the mix.