The Word Insomnia was First Put in the Dictionary 

According to the Online Etymology Dictionary, the term “insomnia” appeared in 1623, was Anglicized as insomnie, from Latin insomnia “want of sleep,” composed of “in”(meaning not) and “somnus” (meaning sleep).

The history of insomnia officially began in 1623 when the word insomnia was put in the dictionary, and it was composed of the word in that means not and somnus which meant sleep. So, as you might expected, even back then insomnia meant no sleep.