He was certainly in bed at the time of the experience, and probably could not be sure whether he was awake or asleep.

{130b} Considering the remoteness of time, the story is very well recorded.
It is chronicled by Mrs.Thrale before the news of Lyttelton's death reached her, and by Lady Mary Coke two days later, by Walpole on the day after the peer's decease, of which he had heard.

Lord Lyttelton's health had for some time been bad; he had made his will a few weeks before, and his nights were horror-haunted.

A little boy, his nephew, to whom he was kind, used to find the wicked lord sitting by his bed at night, because he dared not be alone.

So Lockhart writes to his daughter, Mrs.Hope Scott.