You could try a hammock. The hardly noticeable rocking movement should calm humans and help them getting to sleep, some research said... Aside from that, you always have a view of your surroundings as soon as you lift up your head. You can watch the stars when there's no need for a tarp and you're not on the hard, cold ground.
I have both a tent and hammock and carry one depending on destination, usually don't have sleeping problems though.
I'd advise against alcohol, it might help you get to sleep but the quality of sleep is lower and you might wake up in the middle of the night... Alcohol also dehydrates so drink enough water when using.