When obviously the ethanol content is lower?
Anecdote, not research …
Beer is carby & fizzy. Both of which make me sleepy.
Wine doesn’t make me any sleepier than booze.
The other thing is that the amount of ethanol in a 12 floz beer, a 4 floz wine, and a shot of liquor is not very different. Serving size is everything.
I think that if you compare the sleep-inducing effects of 12 floz of beer versus a 12-floz martini you’ll probably find the martini lays you out faster than the beer will. 
I don’t notice any difference myself. Alcohol might relax me a little, but it doesn’t make me sleepy. (In fact, if I drink enough to start feeling it, it will keep me up.)
One thing to watch with all of these things is that the alcohol per volume varies. Beer, for example, is usually portioned into 12-oz servings, but can vary from about 3% alcohol to 7%, with extremes above and below that. Wines can easily vary from 10% to 15%, again, with some falling above or below that.
So it could be that your choice of styles/brands is affecting your perception?
If I recall correctly, filling your belly makes you sleepy. Going by the drink (12oz beer, 5oz wine, 1.5oz 80 proof spirits), you would get full faster drinking beer and wine.
I don’t like beer and wine, so I have no personal experience.
Rob
My guess is that people tend to drink the alcohol in liquor and mixed drinks faster than in wine, and then beer.
In other words, people tend to drink a 3 oz cocktail a little faster than they might drink a 5 oz glass of wine, or a 12 oz beer. So there’s time in the lesser proof drinks for the alcohol to gradually affect you, while higher proof drinks tend to pound you straight into tipsy or drunk.
The calories.
I personally do not notice any difference other than the fact that maybe I’ll consume the same amount of alcohol more slowly if I’m drinking wine or beer, so I go into the relaxed, but not buzzed stage, whereas with hard alcohol I’ll go into the buzzed stage more quickly. But that’s a big maybe. I personally don’t think I notice any difference. Alcohol does not generally make me sleepy, unless I’m already completely knackered and then a glass of wine or two or a healthy pour of whiskey will send me to sleepville pretty quickly.
I’ve been given to understand that hops, found in beer, are sedating. Though red wine is the one that does a number on me.
Whether alcohol acts as a stimulant or a sedative has more to do with your expectations than with the type of drink. Obviously if you are already particularly tired you are more likely to go to sleep though. That’s why I always like to start nice and early in the day.
I have read, and then believe read a proof that it was untrue, that: you get drunk quicker with carbonated drinks because of the bubbles “force” the ethanol (and everything else?) quicker into your system. :dubious:
More to the point of wine and beer, but similar in science-y approach re absorption: my grandmother, may she rest in peace (“Leo, I was 65 before I learned how to drink Cognac”), told me to always eat a piece of bread with some butter on it before drinking. I don’t get the biophysics of that either.
You’re more often eating when drinking wine and beer.
None of which, I now see has anything to do directly with OP.