That is easily explained by the theory that is us not just the amount of the sleep that counts, but rather the quality.<p>I can wake up after 5 hours of sleep and be completely refreshed. I can also wake up after 8 hours of bad disrupted sleep due to various reasons and feel like a trainwreck the entire day. Including most symptoms in the article, especially if that happens a couple of nights in row: first and foremost the anger (well, mainly the amount of effort it takes to suppress that is killing me) but also the &#x27;wrong&#x27; trains of thought, seeing flashes of things which aren&#x27;t there etc.<p>All of which can then again be rest by 5 (or more) hours of proper sleep.