Why do we say sleep tight?

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Tags

1. #sleep
2. #changed
3. #phrase
4. #people
5. #holding
6. #tight
7. #seems
8. #slept
9. #century
10. #night
11. #soundly
12. #mattresses
13. #popular
14. #according
15. #ropes
16. #meant
17. #later
18. #their