Physical factors making you smarter: white noise, carbohydrates, music, alcohol, and coffee?

• It does seem like coffee makes you smarter, even in small doses. There are several methodological issues however. The main problem is that if you are a coffee user, your brain without caffeine might be negatively impacted due to a withdrawal effect, hence giving you the illusion that caffeine helps. However, it seems that heavy coffee users still outperform before they drink coffee!
• A moderate amount of white noise, such as leaving your radio play a non-utilized frequency at a very low volume, may improve your cognitive ability by increasing your dopamine levels. So if you can’t seem to focus, leaving your office for a coffee place may help. However, it you can concentrate, then white noise may decrease your already-good performance.
• Background music may improve cognitive performance. It seems listening to classical music may makes you smarter. However, a comparison between vocal music, instrumental music, and no music settings showed that on some tasks, no music was always better. A recent paper argues that we cannot trust many studies conducted on human beings, and that we should focus on what happens with animals. I would say that quiet instrumental music might have an effect similar to white noise, and thus, it may mostly help those who have trouble focusing.
• Carbohydrates may have a positive or negative impact on your cognitive ability: eating sugary stuff is probably not useful. However, if you feel tensed, protein-poor and carbohydrate-rich food may help you regain control.
• Alcohol is probably not a good idea.

Disclaimer: this is not meant to be a scientific survey. However, if you disagree with my survey, please do add a comment!

Disclaimer 2: I drink a lot of coffee. I almost certainly reach a point where it impacts negatively my performance because I get too tensed to focus. However, I find it preferable to boredom.