However, various researchers have studied specific types of memories that are most affected by sleep. Researchers have found that some memories are retained better than others; Generally, people remember negative memories better than neutral or positive ones (Payne et al., 2008). This led these researchers to examine whether sleep aided more in the retention of memories of different emotional calibers, and research has indeed shown that sleep aids in the retention of negative memories more than positive ones. I will return to this topic in my discussion of night shift workers and their memories because often jobs that require night shifts are medical in nature and psychologically negative.