Author Interviews, Memory, Occupational Health, Sleep Disorders / 14.07.2015
Lack of Sleep May Impair Memory Functions In Stressful Situations
MedicalResearch.com Interview with:
Jonathan Cedernaes M.D., Ph.D.
Department of Neuroscience
Uppsala University
Sweden
Medical Research: What is the background for this study? What are the main findings?
Dr. Cedernaes: Sleep is known to facilitate the formation of long-term memory in humans, by transferring newly learned memories from short-term to long-term memory stores. Studies however indicate that even shorter periods of sleep - including naps - can ensure access to different types of memories under normal restful conditions. Furthermore, while some studies have shown that acute sleep loss can exacerbate e.g. physiological responses to acute stress, it it has not been studied whether shortened sleep in combination with acute cognitive stress can have a negative impact on the retrieval of newly learned memories.
With this background in mind, we conducted a study where we aimed to investigate how nocturnal sleep duration impacts this memory transfer, and to what extent long-term memories formed by sleep remain accessible after acute cognitive stress.
We recruited 15 participants who in each of two sessions first underwent a learning session in the evening, during which they learned 15 card pair locations on a computer screen. Then, in one of the two experimental session, subjects slept for half a night (4-hr), instead being able to sleep for a full night (8-hr) in the other session. On the morning after each sleep condition, we had the subjects try to recall as many card pair locations as possible. We found that following half a night of sleep (4-hr), participants were equally able to recall memories for the learned card pair locations, as after a full night of sleep (8-hr). However, we also showed that the ability to retrieve memories following 30 minutes of acute stress, in the morning after these two sleep conditions, was different depending on whether the participants had slept for 8 or 4 hours. Following short sleep, the 30-min long stress exposure reduced the participants' ability to recall the card pair locations that the participants had learned the previous night by around 10%. In contrast, no such stress-induced memory impairment was observed when the same men were allowed to sleep for a full night.
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