… so that it doesn’t affect your sleep.

This is how long it takes for the body to metabolise caffeine.
If it really affects you, stop drinking it after midday.

Sources:

Drake C, Roehrs T, Shambroom J, Roth T. Caffeine effects on sleep taken 0, 3, or 6 hours before going to bed. J Clin Sleep Med. 2013 Nov 15;9(11):1195-200. doi: 10.5664/jcsm.3170. PMID: 24235903; PMCID: PMC3805807.

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