The page for John Henry Hopkins, Jr., lists instances of this hymn published when the reputed author, John Hopkins (born 1820), was only 10 years old. For example, first reported instance on this page is in the Christian Lyre, in 1830.
According to Julian, p. 533, the author is Josiah Hopkins rather than John Hopkins (1786-1862).
Comments
Why Sleep We My Brethren
Thanks for pointing this out. I corrected it in the authority and in the instances that we have page scans for.