Will Sleep work the first time I use it? Trish February 11, 2020 17:27 Updated Follow Yes. While individual results may vary, sleep should work from the first time you take it. Related articles When should I take Sleep? Are there any side effects to Sleep? Will taking Sleep make me groggy? Can I take Sleep every night? How is Rae’s Multivitamin different? Comments 0 comments Please sign in to leave a comment.