Thoughts and emotions

we know that your thoughts can influence the neurotransmitters in your brain.

So, if you throw the covers over your head, and that triggers other thoughts such as "I'm tired," "I can't get up," or "Life is hard," complex interactions in your brain may send signals to other parts of your body. 

if you reverse that and think something elke, then the signals will be different.

Your brain is constantly receiving signals, whether from the outside environment in terms of perceptions or memories from your past. It then activates different patterns through waves in the brain through billions of synapses. In this way, your thoughts grow more complex as they interact with other content produced by your brain functions.