While looking for suggested teas to help aid sleeping, I found a piece about a study that has found that green tea (or, more specifically, an agent found in green tea) improves the quality of sleep in young men (perhaps everyone else too, but that’s not what the study was focused on, as far as I know):

The small study used the pure, enzymatically produced L-theanine dietary supplement Suntheanine manufactured by functional ingredients company Taiyo Kagaku Japan.

“Our clinical study strongly suggests that Suntheanine supplementation of young men can improve both the quality of sleep and the mental state of being refreshed on waking up,” said the study’s author, Dr Shuichiro Shirakawa, a professor at The National Center of Neurology and Psychiatry at the National Institute of Mental Health (NIMH) in Tokyo.

Rich in cancer-fighting antioxidants, green tea extracts are steadily being introduced into food and beverage products. The tea’s active agent Epigallocatecin-3-gallate, is thought to aid a wide range of health conditions, notably lower cholesterol, prevent heart disease, fight bacteria and dental cavities, possibly aid weight loss and slow tumor growth in breast and liver cancers.

Only 22 people were tested though so it’s hardly conclusive. Read more.

Oh, and my original search found peppermint, chamomile and rosemary tea to be the most frequently recommended for helping one get to sleep. Although one website also listed peppermint as a refreshing tea for helping you wake up — so perhaps there is no inherent agent that aids sleep, rather it is the warming effect that is soothing when one is ready for bed (and softly invigorating upon waking).