Melatonin Improves Memory Acquisition Under Stress Independent of Stress Hormone Release

The article I chose was called “Melatonin Improves Memory Acquisition Under Stress Independent of Stress Hormone Release.” The researchers of this article were Ulrike Rimmele, Maria Spillmann, Carmen Bärtschi, Oliver T. Wolf, Cora S. Weber, Ulrike Ehlert, and Petra H. Wirtz. This article wanted to determine if melatonin “has a suppressive effect on stress-induced catecholamine and cortisol release in humans.

The sympathetic nervous system can be activated by a number of things, but for this article stress was a major issue. Not only does stress activate the sympathetic nervous system, but it also activates the hypothalamic-pituitary-adrenal axis which then increases catecholamines such as epinephrine and norepinephrine and glucocorticoids like cortisol. The catecholamines have been known to improve memory formations, while beta-adrenergic are known to inhibit memory formation. It is also known that epinephrine, norepinephrine and cortisol influence the ability to remember and code memories. Researchers also mentioned that the pineal hormone melatonin has a direct correlation with regulating catecholamine and cortisol levels. There were two aims in this study: first was to “examine whether melatonin likewise attenuates cortisol as well as catecholamine reactivity to an acute stressor in humans” and secondly “examine whether a modulation of the stress response by melatonin would be accompanies by changes in memory processing.”

 There were a total of 50 males who participated and all were healthy non-smoking and medication-free males. The 50 males were then split up into two groups: 27 were in the melatonin group and 23 were in the placebo group. Both groups participated during three sessions on three consecutive days. On the first day researchers tested the participants for normal cardiovascular functions such as heart rate and blood pressure. They also had to list words that was used to test memory on the second day. On the second day the Trier Social Stress Test was used after taking melatonin to test their memory under stressful times. On the last day researchers wanted to test melatonin levels and see how well memory was retrieved.

The researchers found that melatonin did have an effect on memory functions. Melatonin did improve memory for objects that were partnered with stressors. This was indicated by using a recognition test for the objects used on different days.  

Source:

Rimmele, U., Spillmann, M., Bärtschi, C., Wolf, O., Weber, C., Ehlert, U., & Wirtz, P. (2009). Melatonin improves memory acquisition under stress independent of stress hormone release. Psychopharmacology, 202(4), 663-672. doi:10.1007/s00213-008-1344-z