About four o'clock
She followed the negative with a short explanation . `` I lay down on my bed soon after dinner , not feeling very well , and slept through the early hours of the night . '' `` At what hour did you wake up ? '' `` About four o'clock , or a little after . '' `` Then you were awake an hour before you discovered the supposed burglar in your library ? '' `` Y-yes , '' Helen 's hesitation was faint . `` About that length of time . ''