Your last coffee has a size as well as a time.

“No coffee after lunch” is easy to remember. It leaves out the size of the coffee, the other caffeine in your day and when you actually go to bed. Start with those details before searching for a perfect cutoff.

What a recent trial actually tested.

A randomized crossover trial in 23 young men compared 100 mg and 400 mg caffeine doses taken 12, eight or four hours before bedtime. The higher dose disrupted sleep, including when taken well before bed. The lower dose did not show a statistically significant effect under those study conditions.

That does not prove that 100 mg near bedtime is harmless for everyone. The sample, doses and timing were specific; people differ in sensitivity and in their usual consumption. It also does not make four cups of any coffee equivalent to the controlled dose.

Look at the whole day.

Include tea, energy drinks and other caffeinated products when considering your intake. Serving sizes and caffeine content vary. Read available labels instead of counting every mug as the same unit.

If you want to change the pattern, choose one manageable adjustment: an earlier last caffeinated drink, a smaller serving or a familiar caffeine-free alternative. Keep the enjoyable pause if that is what you value. There is no requirement to replace your afternoon with a complicated supplement routine.

Notice the pattern without grading every night.

A simple note of drinks, bedtime and how you felt can help a conversation with a health professional. Persistent sleep trouble deserves that conversation even if your caffeine habits look reasonable. A beverage change is one practical choice, not a complete explanation for every difficult night.