Same for me. If I spend the whole next day exhausted after sleep deprivation, my emotional state feels really fragile, my decision making is impaired, and everything just feels harder.
It can also worsen any other symptoms -- sometimes the depression itself too. For example, people who experience anxious depression may end in a much worse situation as a result of sleep deprivation.
This study always needs to be qualified with "your mileage may vary".
Exactly. My experience has been exactly the opposite of lessening depressive tendencies.