aon tsuan ar séan VS suain ni séan
Well... I only know séan in the meaning of blessing or charm (cf Gaelic
seun)... personally I would have translated either as "neither
peace/tranquility/sleep nor blessing/happiness/good fortune".
So in Gaelic that'd be "suain no seun"
But songs aren't my forté I haste to add
Am Mìcheal Eile