The Cambridge version of the London statement with regards to rats is certainly true in many parts of Cambridge indeed there are often situations where you may be closer than that to half a dozen or more of them!
This is of course due to Cambridge being an academic city with two universities. This means a lot of my clients come from varying levels of academia ranging from undergraduates to those doing post doctoral work.
Rosemary is one of the main essential oils I use for this group. There is research suggesting it measurably improves recall if used when studying. It is also one of the oils with a research base for its use with ADHD, the other being Vetiver.
So if studying is your thing and you find concentration difficult, think about using Rosemary oil to inhale (place a few drops on a tissue) when studying.
You might also think about getting a break from sitting in front of a computer and getting an aromatherapy massage using Rosemary and or other essential oils.