Charles Dickens, in a piece with the title Night Walks, describes being out in London when most people are sleeping. It's one of my favourite pieces of writing: a fact which is surprising when you realise I am not a fan of Dickens' other work.
This part of the day is the most difficult for me. It seems like the whole world is asleep, and all its bars and restaurants are closed. At times, the overpowering sense of loneliness and isolation, which is the curse of the insomniac, is almost too much to endure. The darkness envelops all, only to be chased away by the dreariness of electric light. Sleep comes easily to some, but not to others.
Maybe it's just my interpretation but, in Dickens' account, he seems to be seeking the company of another human. There is a passage where he comes across a toll booth operator, with a fire roaring in his booth, and wistfully contemplates the chance of passing some of the night in his company.
Perhaps the night is the time when our desire for company is at its most strong. You may have someone lying beside you, but they are likely to be asleep, so all you have is their warmth, if you wish to risk waking them. We can only hope that sleep comes quickly, and that our dreams may supply us, in our slumber, the company we crave in our wakeful state.