In fact, they may stay up so long that they literally drop dead from physical exhaustion.

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According to the U.S. Drug Enforcement Administration, khat can induce manic behaviors, hyperactivity and hallucinations while chronic abuse can result in symptoms such as physical exhaustion, violence and suicidal depression.

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Tait, who returned to action earlier this year after taking a break with mental and physical exhaustion in 2008, has played 22 one-day internationals as well as three Tests for Australia.

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The 25-year-old announced in January that he was suffering from "mental and physical" exhaustion and would be taking a sabbatical from cricket.

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While physical and emotional exhaustion are bound to strike, there are ways of mustering the strength to plow through.

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But there is still something unsettling about Mr Adams's unusual hints of resignation, his references to physical and emotional exhaustion, and the self-pity that for a while at least appears to have displaced the old self-confidence.

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