Hi Fuyutsuki, Chin, i went online to read about longan too.. many sources say they are warming and calming, good for blood regeneration and improve "qi" in the body. It can be a bit heaty though cos longan is high in iron. I got this from a website about TCM cooking:
The fruit (longan), as a traditional Chinese medicine, is used for cardiac palpitations and books recommend an ounce of it steamed with a teaspoon of pickled Chinese dates be consumed once a day. For weakness, and for those with lack of strength during pregnancy, the same amount of fruit is recommended but mixed with two ounces of crystallized brown sugar, one ounce of red dates, and a teaspoon of fresh ginger; these are to be steamed together and this amount eaten once a day.
Whereas for bird's nest, pls be careful not to eat too much. My GP says research has shown that bird's nest actually causes asthma..