While these are interesting findings, there are not a lot of conclusions that can be drawn from this alone. It was a small, short study, and most people likely aren’t choosing to consume caffeine minutes before going to bed.
But putting these findings in the context of what we already know about L-theanine can help you time out when you should ingest these compounds for optimal productivity and sleep.
Caffeine is also best consumed earlier, and most experts recommend having a strict cutoff time for caffeine—approximately six hours before you go to bed.
So to really reap the calm energy that these two ingredients provide, it’s best to drink your green tea or matcha before late afternoon. And if those beverages aren’t your thing, that’s ok. Some nootropics like mindbodygreen’s focus+ contain both.