Is it true that using the automatic swinging yao lan (sarong) can cause damage to the baby brain due to constant swinging motion?

Heard some people mention this and something about their sprain before. But personally felt that it's not; both my sons slept in automatic Yao Lan with no issues. However you might wana take some safety precaution like a mattress underneath the sarong, ensure that the safety rope is secured and etc.