Dose and timing effects of caffeine on subsequent sleep: a randomized clinical crossover trial

This randomized crossover trial assessed how caffeine doses (100 mg and 400 mg) consumed 12, 8, and 4 hours before bedtime affect sleep in 23 healthy young men. The study found that 100 mg had no significant impact on sleep, but 400 mg delayed sleep onset, reduced total sleep time, and disrupted sleep architecture when consumed within 12 hours of bedtime. The effects were more pronounced the closer caffeine was consumed to bedtime. The findings emphasize caffeine's dose-dependent impact on sleep, highlighting the importance of timing and dose in maintaining healthy sleep patterns, which are crucial for brain health and cognitive performance.

To protect sleep quality, limit caffeine intake to no more than 100 mg within 4 hours of bedtime and avoid 400 mg doses within 12 hours of bedtime. This recommendation is based on robust findings from a controlled study, emphasizing caffeine's disruptive effects on sleep. Tailoring caffeine use to individual tolerance and timing can optimize sleep, which is essential for cognitive health and recovery.