Is There a Better Time to Nap?
Sleep can be unrefreshing and the fatigue of fibromyalgia can make getting through the day difficult. One way to help you along might be to take a nap, even if you can only manage it on the weekends. But when you wake up from a daytime nap, you want to minimize the sluggish, mentally slow feeling that may greet you (as though your brain has not snapped out of sleep). So, the question is: should you take the nap in the morning or the afternoon?
A study looking at the after effects of a 10 a.m. versus a 3 p.m. nap in healthy people reveals that morning naps may be best for quicker recovery from sleep.* A research team in Ireland purposefully short-changed their study subjects by two hours of sleep the night before so they would be more tired the day of the testing. Then, they divided the volunteers into three different groups: those allowed a 90-minute morning nap (at 10 a.m.), those allowed a 90-minute afternoon nap (at 3 p.m.), and those who were who were kept awake for the duration of the day (the no-nap group).
Cognitive evaluations and psychomotor vigilant function (i.e., reaction times) were assessed in the two napping groups at both five and 20 minutes after being awakened from their naps. The same tests were done on the control subjects who did not take a nap. The goal of the study was to determine which nap group recovered the fastest from the drowsy effects of sleep.
Healthy subjects in the morning nap group performed equally as well as the no-nap group on the cognitive/vigilant tests. In fact, there was also no difference between this nap group’s test results just five minutes after waking compared to 20 minutes after being awake. In contrast, the afternoon nap group performed poorly after being awake for five minutes, although they performed as well as the sleepy control subjects on the simple tasks 20 minutes after waking.
Looking at the difficulty of the cognitive tests, those that required higher-level functions and greater load on working memory were most affected by the afternoon nap (even after 20 minutes). In other words, napping subjects actually performed okay on the simple “brainless” cognitive tests. So, if you are not planning to challenge your brain after a nap, you may get by with taking it in the afternoon. Ironically, the afternoon nap folks were a poor judge of their post-nap declines in cognition (i.e., they thought they scored much better than they actually did).
What does this study say about the potential effects of napping on cognitive function? Even if you are tired, you may wake up less alert from an afternoon nap. Instead, it may be best to work through fatigue later in the day with less challenging tasks. But a morning nap may not further impair your abilities.
Curious about the working memory tests used by the researchers? This example is a 2-back test, but subjects were also asked to do a more complicated 3-back test. http://cognitivefun.net/test/4
* Groeger JA, et al. Behavioral Neuroscience 125(2):252-260, 2011.