I took melatonin for a week and my dream journal filled up

I flew to a conference in Amsterdam last month. Five-hour time difference, red-eye flight, and I landed feeling like my brain had been scooped out and put back in sideways. A friend handed me a melatonin gummy at dinner that first night. "Take this, you'll sleep." I don't usually take supplements. But I was desperate, so I chewed the gummy and went to bed.

I slept fine. But the dreams were something else.

That first night I dreamed I was performing surgery on a bicycle. Not metaphorically. I had a scalpel, there was a draped surgical field, and the bicycle's chain kept bleeding. I woke up and wrote for ten minutes straight, which almost never happens. My usual entries are three or four sentences. This was a full page.

It happened again the next night. And the next. By the end of the week I had seven entries that were longer and stranger than anything in my journal from the previous two months combined. So I did what I always do when something in my sleep life gets weird: I went looking for papers.

How the extra melatonin works

Your body already makes melatonin. The pineal gland starts releasing it when light dims in the evening, and it peaks around 2 or 3 a.m. It's a timing signal more than a sedative. It tells your brain that it's nighttime.

When you take supplemental melatonin, you're adding to that signal. And one of the things extra melatonin does is shift the balance of your sleep stages. A 1987 paper by Charles Maurizi proposed that melatonin triggers the release of vasotocin, a brain chemical that helps control REM sleep. More melatonin means more vasotocin, which means more time in REM and more intense REM periods. When vasotocin was administered directly to narcolepsy patients, REM sleep duration increased by more than 100 percent.

REM is where most vivid dreaming happens. If you're spending more time there, and the REM itself is more intense, you're going to come out of the night with more to write down.

This is probably what happened to me in Amsterdam. I was taking somewhere around 5 mg per gummy (I checked the label afterward), and my REM sleep was likely getting amplified in a way my brain wasn't used to.

The study that actually tested this

Most of the research on melatonin and sleep doesn't ask about dreams at all. The studies measure sleep onset latency, total sleep time, efficiency. Dreams are treated as a side note if they're mentioned.

But there's one study that went looking for it directly. In 2000, Tracey Kahan and her colleagues at Santa Clara University gave 22 college students either 6 mg of melatonin or a placebo for six nights and had them report on their dreams. They scored the reports for specific types of bizarreness: impossible events, transformations, incongruities.

The melatonin group showed increases in "transformations of objects," the kind of dream weirdness where a thing becomes another thing mid-scene. A bicycle that bleeds, say. The effect was stronger in female participants than male, which the researchers flagged as something worth investigating further. As far as I can tell, nobody has followed up on that gender difference in the 26 years since.

It's a small study with a high dose. But it's one of the only ones that bothered to measure what most melatonin users actually notice: the dreams get weird.

The dosing problem

Something bothered me when I started reading about this. Melatonin is classified as a dietary supplement in the U.S., so it's not regulated the way drugs are. The FDA doesn't verify what's in the bottle.

A 2017 study in the Journal of Clinical Sleep Medicine tested 31 melatonin supplements and found that 71 percent of them didn't match their label within a 10 percent margin. The actual melatonin content ranged from 83 percent less to 478 percent more than what the label claimed. Lot-to-lot variability within the same product varied by up to 465 percent. And eight of the 30 samples contained serotonin, which wasn't listed on the label at all.

So when someone says "I take 3 mg of melatonin," they might be taking 0.5 mg or 14 mg. They have no way to know. And the gummy my friend handed me in Amsterdam could have been anything.

This matters for the dream question because dosing appears to matter. Your body produces roughly 0.1 to 0.9 mg of melatonin per night. Most supplements start at 1 mg and go up to 10. That's ten to a hundred times more than your brain makes on its own. And bigger doses seem to push REM harder.

A lot of people are taking this stuff

Melatonin use in the U.S. has more than quintupled since 1999, according to a national health survey. A more recent survey found that over 27 percent of U.S. adults have used melatonin for sleep. Sales went from $62 million in 2003 to $821 million in 2020.

That's a lot of people taking a supplement where the bottle might not match what's inside, and almost nobody has studied what it does to dreams. A preliminary study presented at the American Heart Association's 2025 conference found that long-term melatonin use for insomnia was associated with a higher risk of heart failure in more than 130,000 adults. That study hasn't been peer-reviewed yet, and correlation isn't causation. But it's enough to make me want to understand what I'm putting in my body before I chew another gummy.

What happened when I stopped

By the time I flew home, my jet lag had worn off and I stopped taking the melatonin. Within two nights, my dreams went back to normal. Shorter entries. Less narrative. The familiar fragments and half-scenes I'm used to waking up with.

I don't think the melatonin dreams were bad. They were actually kind of fascinating to reread. The bicycle surgery dream led to a whole chain of associations I wrote about for days. But the vividness had a forced quality, like my brain was running the dream machine at a higher RPM than it needed to. I slept, but I didn't always wake up feeling rested. That tracks with what the Cleveland Clinic notes about melatonin and next-day grogginess, especially at higher doses.

I find the whole thing interesting on paper. Less so at 6:45 a.m. when my alarm goes off and I feel like I ran a marathon in my sleep.

What I'd think about before taking it

I'm not anti-melatonin. For short-term use, like jet lag or a shifted schedule, it does what it's supposed to do. But I think a lot of people are taking it nightly without realizing what it's doing to their sleep architecture, or that the dose they think they're taking might be wildly off.

If you're taking melatonin and your dreams have gotten unusually vivid or strange, the supplement is probably why. That's not dangerous on its own. But it's worth asking whether you need it, or whether the sleep problem you're solving has a simpler fix. A darker room. A consistent wake time. Putting your phone in a drawer after dinner.

Sleep researchers, including ones at UC Davis, recommend starting at 0.3 to 0.5 mg if you do use it. That's closer to what your pineal gland actually produces. At that dose, you're nudging the signal, not flooding it.

I've gone back to sleeping without it. My dream journal is thinner again. Three sentences instead of a full page. I think I prefer it this way. The melatonin dreams were interesting to read, but they didn't feel like mine.