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

Actually I was totally against it until week 6 when my boy was inconsolable. We gave in but of cos we do not rock vigorously . We also put a mattress below the hammock in case he falls. My boy is now 2.5 years old n he self weaned it by 1 years old. Zzz in it well n pple said his head shape is nice due to him sleeping in it though I'm not sure if it helps. Now with my second child, I put her in when she was week 3. She didn't like it. So it really depend on the baby. Anyway, we all grew up using this last time. I think as parents, we have the decency to know that it shouldn't be vigorously rocking...