Neuroendocronologists report that a nasal spray containing a chemical secreted by the body's own immune system can improve the formation of long-term memories while sleeping. Lisa Marshall and team at Germany's University of Lubeck studied the impact of the substance, interlukin-6, on emotional and procedural memory retention. From the Federation of American Societies for Experimental Biology:

To make this discovery, Marshall and colleagues had 17 healthy young men spend two nights in the laboratory. On each night after reading either an emotional or neutral short story, they sprayed a fluid into their nostrils which contained either interleukin-6 or a placebo fluid. The subsequent sleep and brain electric activity was monitored throughout the night. The next morning subjects wrote down as many words as they could remember from each of the two stories. Those who received the dose of IL-6 could remember more words.