Hanoi, Vietnam | Prolonged illness, spiritual possession, stress over family troubles: Len Dong, or Vietnamese shaman dance, posits itself as a cure for all ails. 

The ancient practice -- previously restricted by colonial France and Vietnamese authorities -- is enjoying a renaissance in the communist nation as officials ease constraints against it.  

Practioners promise to rid followers of evil spirits by using music to lure them out, they also pledge to pass on messages from the dead to the living.

"When I'm in service it seems that somebody lets me in, everything, every word I say, every move I make, I am not myself any more," professional shaman La Thi Tam told AFP.  

In one of her hours-long ceremonies, draped in heavy silk robes, she dances to music, brandishing a sword to attack invisible enemies, periodically drinking and smoking. 

The 50-year-old former folk singer told AFP she started practising Len Dong 15 years ago, after seeing visions of an ancient ruler's spirit in her sleep. 

Sick for a month and barely able to eat anything, she said she was "crawling around the house and uttering weird words".

Desperate for a cure, she decided to try Len Dong but kept it from her policeman husband. 

"Science is outstanding, but my (Len Dong) ideology is super. This can neither be explained nor imagined," she told AFP in her small temple packed with followers.

The ancient Vietnamese custom dating back to the 13th century involves "calling the spirits of the dead into the bodies of the living to connect past and present," according to "Len Dong Ceremony: History and Value" by Nguyen Ngoc Mai, one of the main research books on the topic. 

It was officially banned by communist authorities until the 1980s, dismissed as superstitious or even fraudulent with some fake practitioners seeking popularity and riches, but the spirit ceremonies persisted in secret. 

In the late 1980s, spiritual and religious practices were given a bit more breathing room as the country gradually opened up, allowing Len Dong to come out from the shadows. Today, it is quietly tolerated by authorities.  

"All three of my children practice Len Dong," said shaman Dao Thi Huong.

She feared her children inherited so much bad luck from their ancestors that they risked early death.  

"I was very scared. If they didn't participate in services, they would have died," the 46-year-old told AFP. 

Len Dong can help people under intense stress or suffering from minor psychological disorders, according to Mai's book.   

But the practice remains shrouded in controversy, and many doubt it is grounded in science, as followers believe.  

Scientific or not, Len Dong followers stand by it.

Amateur practitioner Nguyen Thanh Tung explained: "Those who don't understand may say I am