Sleep

It’s well known by now that a lack of sleep can interfere with learning and memory. What’s relatively less studied is how sleep deprivation affects the memories we form of our personal experiences.

Recently, a group of researchers from Iran and Germany delved into this question. In their study, they turned to a sample of people with high rates of sleep deprivation: nurses. They recruited a group of 25 sleep-deprived night-shift nurses and a non-sleep-deprived group of 25 nurses with a comparable distribution of age, gender, employment status and education.

Then they had the nurses complete a task designed to test autobiographical memory. The nurses were given a series of cue words, each of which was either positive, negative or neutral. Based the cue words, the nurses then recounted relevant memories of their past experiences.

As it turned out, the sleep-deprived and non-sleep-deprived nurses had significant differences in the autobiographical memories they recalled.

For starters, the sleep-deprived nurses recalled fewer positive memories and more negative memories. Their memories were also less specific, and they had worse autobiographical memory in general.

The study also found that the sleep-deprived nurses had higher levels of depression. Although it’s not clear how the nurses’ mood changes relate to their changes in autobiographical memory, previous research has connected depression with impaired autobiographical memory and overly general autobiographical memory. In fact, the link between depression and autobiographical memory is so strong that some researchers have even proposed therapies that target autobiographical memory as a treatment for depression.

This study highlights two major kinds of changes in autobiographical memory that seem to come with sleep deprivation: less specific memories, and a more negative bias in memories. These changes, in turn, may go hand-in-hand with changes in mood, providing more evidence for the importance of sleep in mental health.

Image: Flickr/Jesse Loughborough