Letter: Testing times

I AM inclined to take too much on trust, particularly in the scientific field. However, even I baulked at the claim in 'Mixing a mean testosterone' (Review, 26 September) that older men have 'fewer erections during sleep'. How does anyone know that? Sleep precludes self-reporting, and 'fewer' implies comparison, even a control group.

Does this mean that somewhere, at night, orderlies patrol dormitories exclusively occupied by sleeping men aged, say, 18 to 60 (with a sufficiently large sample to give a meaningful result, requiring, say, 50 or 60 sleepers) and once an hour, on the hour, whip off the sheets and record the results on a clipboard?

Tony Glover

Newcastle upon Tyne