"I do not doubt your vigilance." That would be most unkind, for all that she doubts Alistair in general. "Sleep does not often come to me easily."

Less so down here than normal, but it is better to attribute it to a constant issue rather than point out 'you and your fellows are strange and secretive and it does not inspire confidence when I must trust you with my life'. That...is not entirely politic to say.