OK...I have dug up some articles prior to 1997, text reading "co-sleep", "co-sleeping" and "co-sleepers".
Here iS ONE: Sudden Infant Death Syndrome in Cross-Cultural Perspective: Is Infant-Parent CoSleeping Protective?
By: James J. McKenna
Annual Review of Anthropology 1996
Volume 25 pages 201-216
(sorry...I don't know how to provide the link!)
THESE TERMS HAVE BEEN AROUND LONG BEFORE ARM'S REACH APPLIED FOR THEIR TRADEMARK!!!
Yes, I agree that a trademark should be granted to protect those goods/services of a company ....but in this case, the word has been used before the application date.