However, various researchers have studied specific types of memories that are more affected by sleep. Researchers have found that some memories are better preserved than others; generally, people remember negative memories better than neutral or positive memories (Payne et al., 2008). This led these researchers to evaluate whether sleep aided more in the retention of memories of different emotional calibers, and the research indeed showed that sleep aided more in the retention of negative memories than positive memories. I will return to this in my discussion of night shift workers and their memories, as often jobs that require night shifts are medical in nature and negative in the long run.