I have been down to look at that room again in daylight, for I must know the truth. 

Even if today's entry was short, it was extremely concise in explaining the declining mental state that Jonathan is dealing with it, on top of taking a huge peek inside his dilemma in the castle.

It has been sadly established that Jonathan is suffering greatly thanks to the Count purposefully messing up his sleep schedule, and abruptly revealing all of the supernatural stuff he can do in situations in which Jonathan doubts his own mind.

Did he truly saw the Count go down in his lizard fashion, or the lack of sleep is getting to him? Did the three Weird Sisters actually existed, or that awful experience was just another nightmare? All of this is the result of Jonathan just trying to make sense of anything he sees as he jumps from his own shadow, and deals with nightmares. It's the expected result that Dracula wants to extend this obligatory play in which Jonathan can't get out alive.

However, even if today ends with a note of fearful realization, it was not in vain.

When I got to the doorway at the top of the stairs I found it closed. It had been so forcibly driven against the jamb that part of the woodwork was splintered. I could see that the bolt of the lock had not been shot, but the door is fastened from the inside.

How joyful is to find something, anything, that proves that such traumatic event did happen. That your mind is not playing games with you.