Before revision:  On the other hand, the total duration of drawdowns of a time series, or equivalently the number of its upper price records, follows a Gaussian distribution that depends on its true Sharpe ratio. Reversely, this suggests an estimator of Sharpe ratios based the total duration of drawdowns.
After revision:  On the other hand, the total duration of drawdowns is shown to be an efficient and robust estimator of Sharpe ratios based the total duration of drawdowns.