amounts of sugar/sugar-substitutes), or coffee (like teas also containing various bioactive polyphenols). It is at least one of the world's most consumed drugs. Various natural biochemicals and herbs are investigated for similar or antifatigue effects, as well as other potentially negative as well as positive effects, such as rhodiola rosea. Various psychostimulants like bromantane are also investigated as a potential treatment (or complementary component of such) of numerous neurological disorders. Alkaloids theacrine and methylliberine (Dynamine) are structurally similar to caffeine and are less commonly also used as energizers (e.g. both in combination with liberine), and, like l-theanine, may potentiate and synergize with caffeine in ways some may consider beneficial. During the Second World War, US soldiers and aviators were given benzedrine, an amphetamine drug, to increase their alertness during long periods on duty. While air force pilots are able to use the drug to remain awake during combat flights, the use of amphetamines by commercial airline pilots is forbidden. British troops used 72 million amphetamine tablets in the second world war and the RAF used so many that "Methedrine won the Battle of Britain" according to one report. American bomber pilots use amphetamines ("go pills") to stay awake during long missions. The Tarnak Farm incident, in which an American F-16 pilot killed several friendly Canadian soldiers on the ground, was blamed by the pilot on his use of amphetamine. A nonjudicial hearing rejected the pilot's claim. Amphetamines are used by college and high-school students as a study and test-taking aid. Amphetamine increases energy levels, concentration, and motivation, allowing students to study for an extended period of time. These drugs are often acquired through ADHD prescriptions to students and peers, rather than illicitly produced drugs. Cocaine is also used to increase alertness, as is coca in the form of coca tea. The eugeroic modafinil has recently gained popularity with the US Military and other militaries. It increases alertness but, having a long half-life, delays or impairs sleep-onset, with there being no marketed shorter-acting version. Other approaches for increasing alertness Beyond good sleep, physical activity and healthy diet, a review suggests uses of odours, music and extrinsic motivation may have the potential to increase alertness or decrease mental fatigue. Short rest periods and selected lighting (level and type of) may also be useful. Various types of neurostimulation are being researched, as is the microbiome and related interventions. Alertness after waking A study