All I can think of is Nyquil. Do sleeping pills do this, too? Prescription opiates? I’m asking for a short story I’m writing, and I don’t have any experience with this. Illegal substances are out, because my main character could be described as lawful-neutral.
Sex? 
Kava kava, taken in rather large quantities, would work. Valerian and passionflower, skullcap and hops. Even chamomile tea hits some people pretty hard.
My medicine making notes from my first year of herb school are pretty hilarious. I made a medicinal strength chamomile tea (1 T herb to 1 cup hot water, much stronger than Celestial Seasonings), and reading where I recorded my observations, my handwriting gets bigger and loopier, before it ends in a scrawled"…I think I’m gonna take a short nap…". The next note was that I woke up 15 hours later. Now, chamomile tea, even very strong, doesn’t hit MOST people like that, but some people are more sensitive to its effects than others, and I seem to be one of them. I swear, you could probably put stitches in me with nothing more than strong chamomile tea to dull my brain!
Benadryl (diphenhydramine), used as both an antihistamine and an OTC sleep-aid.; you can get really gorked on that stuff if you have a cold (or not).
Opiates too, though if your lawful-neutral character is using recreationally that might not be an option, prescription or otherwise.
Yep. Diphenhydramine is the additive to Tylenol Nighttime and other pain reliever/help you sleep medications. I came in to say that, and also the motion sickness drug Dramamine (dimenhydrinate). Both are antihistamines, and both are sometimes recommended to give to pets, too, to calm them for traveling.
Last I checked, alcohol was still legal. It’s certainly been known to give a dopey, drowsy feeling.
Nyquil is 50 proof and comes with its own shotglass.
edited to add: It used to be; I don’t know if it still is.
Actifed for a cold. Always makes me feel numb.
They don’t always have that effect - they make me bitchy rather than drowsy - but as this is a story, your character can react any way you want him to :).
Opiates would do the same for most people; if he’s got a legitimate reason for taking them (e.g. migraine or whatever), that might fit the story.
Sleeping pills will get one pretty groggy. And can lead to unintentionally hilarious situations as well (see numerous threads on this board, search for “Ambien”).
Another strongly sedating antihistamine is doxylamine.
Just pointing out the username/post combo, folks …
DXM, the active ingredient in Robitussin would probably fit the bill.
Nutmeg will also cause a similar sensation albeit with unpleasant side effects.
Prescription opiates probably define “that dopey, drowsy feeling,” as in they induce the dopey, drowsy feeling that other drugs should aspire to. Antihistamines, poppy tea (this could fall into a legal gray area), kava, benzodiazepines (Xanax, Valium, Klonopin, etc. prescription but legal and widely prescribed) would also fit the bill nicely. You could say nitrous oxide produces a “dopey, drowsy” feeling, but it goes away within seconds/minutes once you stop inhaling the gas (also, likely somewhat illegal depending on jurisdiction, how used etc.)
Kava Kava is the only thing even similar to a Valium type of relaxation. I have taken Benadryl and it does make me tired but it’s not a good tired. I feel odd the next day, I guess like a hang over (I don’t drink so I don’t know what one feels like)
Seconded on the poppy tea. I used to make it often for guests and also to impress ladies whom I had over at my place. While most of the opium gum is already extracted out by the time you get your hands on them, there’s still enough left to produce a very dopey and drowsy feeling that falls short of a full-on opiates nod. Not sure on the legality of growing and selling poppies, but I’ve known a few people who grew their own (with a great deal of difficulity, admittedly) without any legal problems.
All of the above, and add melatonin tablets, if I missed it somewhere. Supposed to be for sleeping, but it tends to make me stoned off my ARSE. With eyes that won’t close, of course, but hey. I don’t really care if I can’t sleep when I am floating somewhere 12 feet off the ground. >.< But Dramamine, the one time I took it, put me into a near coma for so long the boat was getting ready to head for the nearest hospital <200 miles away>, so I am not sure I’m the best litmus for what ‘normally’ affects people in what way.
Oh, and several types of anti-psychotics definately put you in a dopey mood-----especially older ones like Haldol and Thorazine.
Seroquel, a newer type of anti-psychotic, is getting a lot of off-label prescribing due to its sedative effects------it’s being given for anxiety, PTSD, insomnia, etc.
Also, a short note on presciption opiates…they sure do make you dopey, but not always drowsy. I used to get very energized and alert after using oxycodone and hydrocodone.
The only presciption opiate that made me drowsy was morphine.
In case it relates to the story in any way, remember that some people are opiate-immune.*My sister is one of them.
*General description, not a technical one. Opiates simply do not ‘work’ for some people, in any way. I’m sure it’s not an immunity, but don’t know if there’s a name for it.
Combine Melatonin with Nyquil - take them both at the same time. It gets you very dopey, drowsy and euphoric. It feels great! It’ll give you that “just starting to fall asleep” dreamy stage, but prolonged, and then you will sleep. But you better have TIME the next day to sleep in, because you won’t be awake for 12 or 14 hours!