Fri. Jan 28th, 2022

    Sleep enhances memories. It makes them stronger and more effective.

    I found myself lying flat on my back in the middle of shop last weekend.  A robotic bed hummed and gently jiggled underneath me while I watched a presentation on a strategically placed screen just to the left of where I lay.  After 3 or 4 minutes of humming and jiggling, the computer spat out a report listing a range of mattresses that suited my individual sleep needs — $5839 for the best match.

    Marketing ploy? Absolutely!  We haven’t handed over any money yet. But I was completely won over by the Sleep 101 presentation that was shown during my ‘mattress fitting’. They had the science of sleep pretty well spot on when they stated…

    Sleep is essential to your body’s overall wellness, both physically and emotionally

    But you know that, right?  I’m not going to dwell on the benefits of a good night's sleep in this blog post, because we’re all very well aware of how terrible we feel without adequate sleep.

    Instead, I’m going to focus on my other favourite sleep issue, one that I’m a passionate devotee of — the afternoon nap!

    Professor Leon Lack, sleep scientist at Flinders University in Adelaide says,

    A brief nap can not only reduce sleepiness but also improves cognitive functioning and psychomotor performance (the brain telling the body to move). A few minutes of shut-eye also considerably enhance short-term memory and mood.

    A quick backgrounder in sleep …

    Sleep is divided into two major phases of brain activity but named after eye-ball movement …

    rapid-eye-movement (REM)
    non–rapid-eye-movement (NREM) sleep.

    When you first fall asleep you experience NREM sleep, and then 60 to 90 minutes later, REM sleep kicks in. During the course of a normal night, a healthy adult will experience 4 to 6 consecutive sleep cycles of REM and NREM.

    When you’re in NREM sleep, your body is able to move, but your eyes don’t; your breathing  and heart rate slow and your blood pressure falls. Blood flow to the brain decreases, and electroencephalograms (EEGs – recordings of brain activity) show slowing of brain activity.

    When you cycle into REM sleep, your body becomes immobile and yours eyes move about rapidly. Your blood pressure, heart rate, and breathing rate increase, and blood flow to the brain increases (and my gentlemen readers can attest to blood flow into other areas of the anatomy too). EEG activity also increases and you being to dream.

    You also dream just as you enter NREM too.

    Neuroscience has shown that …

    NREM sleep is essential for learning and memory

    Neuroscientists have been gathering evidence for some time that rats need NREM sleep to learn.  Patterns of electrical activity recorded from brain cells in the hippocampus (the brain structure involved in learning and memory) when rats explored a maze for the first time were repeated again in the hippocampus during post-learning sleep.

    Scientists think that the maze memories become consolidated during NREM sleep.  Rats that were deprived of post-learning sleep were worse at finding their way through the maze compared to rats that slept.

    This experiment has been repeated in humans.  People were invited to spend a day in the lab with Harvard sleep scientist Professor Robert Stickgold. They were trained to navigate their way through a virtual map at around lunchtime and then tucked up for a siesta immediately after.  Neuroscientists monitored their brain waves via EEG and woke them if they started to fall into REM sleep. A second group of maze navigators were left to sit quietly but not nap.

    The people who napped performed much better than the non-nappers when they were retested at navigating the maze.

    Professor Robert Stickgold says,

    Sleep enhances memories.  It makes them stronger and more effective

    My ongoing afternoon siesta research has taught me that the key to making the most of the afternoon nap is to keep it short. When I feel the mid-afternoon slump coming, I give in to it! I set my iphone for 30 minutes so I don’t fall into deeper sleep (and I assume without running my own EEG that I’m avoiding REM sleep), and I never wake feeling groggy. It might sound indulgent, but I like to apply neuroscience research to my daily life! So there you have it …

    Boost your memory and mood by taking a short afternoon nap



    Do you ever indulge in an afternoon nap? Leave a comment below and tell me if you'll be more likely to try to fit in a siesta after reading this post.
    Brooks & Lack. 2006. A brief afternoon nap following nocturnal sleep restriction: which nap duration is most recuperative? Sleep. 29(6):831-40.  Wamsley, Tucker, Payne & Stickgold. A brief nap is beneficial for human route-learning: The role of navigation experience and EEG spectral power Learn Mem. 2010 July; 17(7): 332–336

    The post The neurobiology of the afternoon nap appeared first on Your Brain Health.

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