If there’s one thing to know about me, it’s that I never quite outgrew the afternoon nap phase we all went through as kids. Among my friends, napping was (and still is) considered to be my “thing." From my friends creating a photo album of me dozing in the library to getting me a pajama set for my birthday, it’s been a hard reputation to shake. As someone who consistently gets slammed with the strong yearn to catch some post-lunch Zzz’s, the caffeine nap strategy is one I find fascinating.
For those who are not as well versed in napping strategies, a caffeine nap – a.k.a. the nappuccino - is when you take a power nap immediately after consuming a caffeinated beverage. Of course, this method sounds incredibly counterintuitive, but there may be something to this napping method. In my lifetime, I have taken a handful of caffeine naps, and I must admit that I have felt more refreshed after doing so. But why? Is it just placebo, or is this an untapped gold mine for my fellow sleepyheads? To begin to understand this mystery, let’s look at the function of the organic compound, adenosine.
While to us, sleep may feel like a very simple state, brain on, brain off, it is in fact a complex process carried out by many systems within our bodies. So, while this article will mainly focus on the role of adenosine receptors in regulating sleep, just know that this is only one aspect of what goes on when we are in dreamland. The Adenosine Sleep Theory was conceived of by researcher Miodrag Radulovacki in 1985. This hypothesis was developed using evidence in cats and rats. Among these organisms, adenosine levels increased during wakefulness and decreased during sleep. These preliminary findings inspired sleep research in humans and continued animal research, which supported the hypothesis of adenosine playing a role in regulating sleep homeostasis.
A good way to conceptualize adenosine is to think of it as the currency through which our brains measure time being awake. Essentially, more adenosine builds up in our brains the more active and alert we are during the day. When we sleep, adenosine is recycled, and its levels in our brain are reduced. When there is less adenosine receptor stimulation, we feel more awake. Conversely, the longer we are awake, the more adenosine we produce and therefore the more tired we are at the end of the day. When we introduce caffeine into the equation, things get a bit more dicey. Caffeine binds the same receptors as adenosine, effectively making it adenosine’s arch nemesis. Because caffeine, among its many other effects on the body, binds to adenosine receptors, it promotes alertness as adenosine has fewer open receptors to bind to.
This is where the caffeine nap comes in. When you drink a caffeinated beverage, depending on your age, weight, most recent meal, etc. it takes between 15 and 60 minutes for the effects to settle in. This is the window in which the nap-step of the two-step caffeine nap process occurs. Based on knowledge surrounding the impact of sleep on natural adenosine levels, it has been hypothesized that during the nap, adenosine levels decrease, which free adenosine receptors, allowing caffeine to bond in adenosine's place. The result of this is waking up from a nap both refreshed and caffeinated. That is why users may feel that these naps are more effective and leave them feeling much more awake than if they had just taken a 20-minute power nap.
While an interesting idea, this process lacks the necessary scientific evidence to support it. There have been few studies that look specifically at the mechanism of action behind caffeine naps, and the ones that do are not as methodologically robust as we would like them to be. For example, a 2020 pilot study found that individuals who took caffeine-naps during a lab-simulated night shift had less performance impairment than those in the placebo group (a regular nap with no caffeine). However, this study only included 6 participants, so the results should be interpreted with caution. Additionally, this study looked at more extreme instances of sleep deprivation, rather than your typical midday sleepiness.
This also begs the question of whether this method holds up first thing in the morning. Surely if you are to feel a boost of wakefulness after a caffeine nap, then wouldn’t this be a foolproof way to truly become a morning person? Not necessarily. The research in this domain is not only limited, but conflicting. Some proponents go as far as to say that caffeine should be avoided until at least 60 to 90 minutes after waking up, while others say that it makes no difference.
The moral of this story is that we don’t really know how effective caffeine naps are – if at all. But, hey, when it comes to getting reenergized in the middle of the day, maybe a placebo is all I need. Perhaps you can experiment with a friend who is also a fan of this method, but slip them a decaffeinated coffee rather than a caffeinated one...
Eva Kellner is a recent graduate from the Faculty of Arts and Science, with a major in Environment. Her research interests include urban green spaces, urban agriculture, and outdoor community spaces - all as promoters of climate resilience among city-dwellers.
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