Let’s continue on our topic of naps in healthy adults- the good, the bad, and the otherwise.
Some more good news about napping. As we all have probably experienced in our life, a short nap has helped us learn something that we simply couldn’t grasp beforehand. This is because after intense work, parts of our brain begin to show signs of information saturation, meaning our brains are at capacity and we consequently have problems processing further information. One study found that learning of a task requiring visual discrimination (our ability to differentiate different objects based on their individual characteristics), improved after only 60-90 minutes of daytime sleep. The benefits found in the short afternoon nap actually matched those seen after a full nights sleep, and added to the improvements seen in learning with the following nights sleep. Similarly, in a different study an individual’s ability to think was improved after a brief nap.
When is the most opportune time for nap? I know you’re thinking- whenever I can, but I mean when is a nap likely to do the most good? The answer is that around 3 PM is probably the best time for a little siesta. This actually has some biological underpinnings. In the past we have discussed the idea of our internal body clock or circadian rhythm, which regulates our levels of arousal and sleepiness through the day and also maintains the flow of our biological processes in the body. Our clock usually has an ebb sometime after lunch (whether you ate lunch or not), typically between 1-4 PM, when our daytime arousal levels decline. In addition this is around the mid point of the day and an appropriately timed nap can improve functioning for the remainder of the day.
Now for the bad. What could be bad about a little nap? The major drawbacks are lost productivity while sleeping, the occurrence of sleep inertia (see below), potential long term health risks, and the possibility that daytime naps may worsen the quality and quantity of nighttime sleep.
Interestingly in early 2006, the Spanish government, the probable birth place of the siesta, enacted regulations stating that governmental offices should have 45 minute lunch breaks and send their workers home by 6:00 PM. This was done because under the previous schedule, with a lunch break between 1:30-4:30, in addition to long commuting times, many Spanish workers out of the home for more than 12 hours per day. In addition, the long lunches did not keep them on the same schedule as other European governmental workers, was felt to limit productivity, and decreased family time.
What is sleep inertia? Sleep inertia is that feeling we get in the morning that stays around until we have our morning coffee and have taken a shower. It is the time it takes for us to “get going” in the morning. It has been shown to decrease the ability to perform tasks that require manual dexterity and leave us with a feeling of grogginess. This can cause some impairment in alertness and performance for approximately 30 minutes after awakening from a nap. Sleep inertia can probably be minimized by limiting the nap to between 20 and 45 minutes, as the deeper stages of sleep are more likely to cause sleep inertia.