Okay, more like anectocal trials than clinical trials but - the stuff sure works!
I had to experiment with the dosage though, due to my lactose intolerance (if you didn't know, Horlicks contains both skim milk powder and a separate amount of lactose, plus you have to make it up with fresh milk). The first evening, I made myself a full cup of the stuff and my anticipated sweet dreams were replaced by a disappointing case of "the trots".
The following evenings, I reduced my dosage to half a cup of the drink (minus the small amount which boiled over the edge of the cup in the microwave oven). This resulted in either a full night's sleep, or only minor awakenings (as opposed to being wide awake, getting out of bed, going to the toilet, watching Animal Planet on the telly and eating toast whilst waiting to feel sleepy again).
On Wednesday evening though, I missed my dose because of my cold. I was so full of mucous already, and decided I didn't want any more. And on that night I had a lousy night's sleep.
Last night I was back on the Horlicks, and sleep was fine and full of pleasantly interesting dreams.
So there you have it - Horlicks puts you to sleep. I'd be happy to recommend it, especially if the makers put money in my hands to say so on TV.