Let me begin with facts—bare, meagre facts, verified by books and figures, and of which there can be no doubt. I must not confuse them with experiences which will have to rest on my own observation, or my memory of them. Last evening when the Count came from his room he began by asking me questions on legal matters and on the doing of certain kinds of business. I had spent the day wearily over books, and, simply to keep my mind occupied, went over some of the matters I had been examined in at Lincoln’s Inn. There was a certain method in the Count’s inquiries, so I shall try to put them down in sequence; the knowledge may somehow or some time be useful to me.
Harker carries on in Dracula's castle pretending that he isn't a prisoner. Whether or not Dracula is aware of this, is uncertain. Neither man is revealing what they know and Harker, in particular, is actively trying to thwart Dracula's plans.
Dracula and Harker discuss the various points of having a single legal or business representative in England versus several. Dracula states that he has interest in London and various other locations. Harker is disappointed to learn that Dracula wants him to extend his business trip for another month. After this conversation, Harker writes a letter to Mina and some correspondence for Dracula. Dracula writes his own letters which Harker tries to spy on. They include the names of several representatives in Varna, Budapest and London. Before he leaves Harker alone, he warns him to stay in his own rooms at night or any time he feels the need to sleep. The castle is dangerous.
Harker returns to his bedroom but is unable to relax. He walks to a tower with a southern facing window to admire the night scene. He muses that being awake only at night has made him anxious and a bit paranoid. It is then that he sees Dracula at a nearby window. He is horrified to see him climb out of this window and crawl along the wall of the building like a reptile. This journal passage ends with the hint that Harker than experienced a terror induced panic attack.
I'm not surprised that Harker is having problems with being forced to adopt a night shift existence. According to the latest science, night shift hours interfere with the body's natural bio-rhythms. It creates hormonal havoc in people leading to such diseases as Diabetes and Heart Disease. It also contributes to depression and acuity problems due to lack of sleep.
HERE is an interesting article on the bad effects of being on the Night Shift. This link looks at the problem from a psychological perspective.