L-Theanine at 200–450 mg daily may improve sleep quality, with little change in hours slept. That was one takeaway from a review covered by NutraIngredients. Researchers at The Water Street Collective examined L-Theanine and its effects on thinking, mood, and sleep. They drew on earlier reviews that combined results from human studies. Those studies assigned people to different treatments by chance. The findings described in the article focused on healthy adults. The key sleep finding was about quality, not extra hours. The review found signs of better sleep at 200–450 mg daily. It reported little effect on Sleep Duration. The excerpt did not give a number for how much sleep quality improved. It also did not say how long those benefits lasted. Other findings help put the sleep claim in context. Doses of 100–400 mg produced small gains on some thinking tasks. These were most apparent on visual attention tasks and with caffeine. At 200–400 mg daily, some studies reported less stress and Anxiety under stressful conditions. Those changes occurred without making people sleepy. There is also a business connection worth noting. The Water Street Collective sells drinks containing L-Theanine under its Ryde brand. It is owned by British American Tobacco. This does not settle whether the findings are right or wrong. But it matters when weighing the review’s claims. For BioSocial members, the useful distinction is feeling better rested versus sleeping longer. Tracking both can make community comparisons more meaningful. Notes on dose, timing, caffeine, and other routine changes add context. Personal logs can reveal patterns, but cannot prove what caused them. If you’ve tracked L-Theanine, what changed in your sleep quality or nightly numbers?