Sleep
Sleep quality, duration, and sleep aids.
AshwagandhaPromising stress findings, from a narrow and mostly industry-funded literature.Mixed findings154 papersCaffeineThe world’s most used stimulant, and a well-tested ergogenic.Well supported206 papersMagnesiumEssential in the diet, widely supplemented, thinly trialled.Promising but early320 papersMusicReal effects on anxiety and pain, in trials nobody can blind.Promising but early318 papers