Anger🤬 car crashes🚔 depression😟 and low energy🥱 are all caused by insomnia. The Ancient Greeks wrote about it and the modern Greeks devised the official medical measure (The Athens Insomnia Scale in case it comes up in a pub quiz).
Insomnia causes misery for millions of people. Sleep is deeply complex and not entirely understood – though it is known to be absolutely essential to health and well being. Why humans evolved to need sleep – or why we are not like dolphins🐬🐬 (half of their brain goes to sleep at a time while the other half stays alert) no one knows🤷♀️