Sleep and anxiety can negatively impact your sleep because they can trigger the release of hormones, such as cortisol. Note that cortisol levels naturally increase about two to three hours into sleep, which is why most of your deep sleep usually occurs in the first half of the night as cortisol decreases slow-wave sleep. So, if you have high cortisol levels due to stress or anxiety before going to bed, you might not spend enough time in those restorative sleep phases. As such, if you have trouble sleeping, do things that relax you, like taking a hot shower or reading a book. Also, nasal breathing relieves anxiety and I practice it every day.