Noise,

...daily intake recommended.

I think I would go crazy without these items, I don't like silence... they are also very useful when people have to be ignored ;)

Third day in a row of running around the lab for 10 hours, with no breaks. Think I can say that I'm tired now!
Tomorrow I will not get up before 6am, and I will be the first one to leave the office! No matter what! :)