Sleep plays a vital role in our lives, yet many people experience sleep deprivation and sleep disorders that prevent them from getting adequate rest and being able to function well during the day. Not feeling emotionally well can be the cause of sleep deprivation. This study aims to investigate the relationship between emotional state and individual sound preferences to fall asleep. The study focuses on environmental sounds rather than music as the use of these sounds for sleep is under-explored. An online survey was conducted to assess whether people prefer different sounds to aid sleep depending on their emotional state. The results show that sounds such as Rain, Underwater sounds, and Singing Bowl sounds are preferred for negative emotional states. On the other hand, the sounds of Birds, Crickets, and Rain are selected more often for positive emotional states. Additionally, the paper describes the initial stages of a mobile app development that we are planning to use to implement the study’s findings. The app asks the user for their emotional state and suggests to them three different sounds to regulate their emotional state and help them fall asleep.