| Population | Included: Studies of healthy participants of any age. Excluded: Studies of participants with severe symptoms of depression, schizophrenia, a mental health disorder, Alzheimer’s disease, dementia, or any condition that requires institutionalization or intensive pharmacological intervention that could be expected to interfere with any of the primary outcomes.
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| Intervention | Included: Studies of interventions of tea (Camellia sinensis) and/or the combination of theanine and caffeine, and/or theanine. Excluded: Studies with co-intervention(s) from which effects of tea/theanine could not be disentangled and studies using tea interventions that contained only polyphenols, flavonoids, and catechins.
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| Comparison | Placebo/water, coffee, caffeine |
| Outcome | Cognition (Harvey, 2019)29 and/or mood and/or sleep outcomes |
| Study design | Included: Randomized controlled trials. Excluded: Exposure, observational, and animal studies; systematic reviews; meta-analyses; and abstracts were excluded.
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