Research has made it more and more apparent that lack of sleep has many detrimental effects like worsened daytime alertness, increased inflammatory response, poor blood sugar regulation, and increased sleepiness during waking hours (Pejovic et al.). But if I sleep extra on the weekends do I actually "catching up" on anything? According to Pejovic and colleagues, the answer is no.
The recent study found that subjects who were restricted 2 hours of sleep (6 hours of sleep instead of the recommended 8) for 5 days were significantly sleepier while taking objective and subjective cognitive tests compared to baseline, and their performance on the test was significantly lower. They also had elevated levels of interleukin-6, an inflammatory marker, but their cortisol levels, an indicator of stress, remained the same. This isn't surprising. Many of us know that a good nights sleep before an exam is important for memory processing and recalling. So, if I stay up every night to study for an exam and then have a full night's sleep the day before, will I perform just as well? According to this study, the answer is still no.
After the initial 5 day restricted sleep periods, subjects were allowed 2 days of "recovery sleep", during which they slept for an extra two hours (10 hours total each night). While sleepiness decreased, levels of interleukin-6 were lowered, and levels of cortisol decreased, subjects performance and alertness still did not improve on the objective and subjective tests. This suggests that while certain physiological factors are improved with extra "recovery" sleep, not all are. Perhaps there is another factor caused by lack of sleep contributing to the poor test performance of these subjects. It seems that two nights was not sufficient for the subjects to improve on their alertness. Perhaps an extra day of sleep may help? What do you think? Knowing this, would you still sacrifice some sleep to get that extra hour of studying in, or would you forgo the cramming and climb into bed for some shut eye?
References:
Pejovic S, Basta M, Vgontzas AN, Kritkou I, Shaffer ML, Tsaoussoglou M, Stiffler D, Stefanakis Z, Bixler EO, Chrousos GP. 2013. Effects of recovery sleep after one work week of mild sleep restriction on interleukin-6 and cortisol secretion and daytime sleepiness and performance. Am J Physiol Endocrinol Metab. 305(7): E890-E896.Available at: http://ajpendo.physiology.org/content/305/7/E890
This is a very interesting post. I have always been really intrigued by sleep, especially in my Neuroscience classes. It has come up before in those classes, actually, that there really is no such thing as "catching up" on your sleep. That being said, I do, and will continue to, forgo the late-night studying and cramming sessions just so that I can get the necessary amount of sleep. Not getting those essential 7-8 hours really affects my performance during the day, and with a busy schedule like mine, I really can't afford to have days where I am groggy and not alert. Getting enough sleep is especially important when people are trying to remember things (such as material for a test). It is widely believed by scientists that memory consolidation occurs when we sleep, particularly during the REM sleep stage in our sleep cycle. Thus, if we do not get enough sleep cycles in over the course of the night, we do not get enough time to process and program the memories we want to. There is a lot more information about the affects of REM vs. Non-REM sleep on memory consolidation and learning on the website below. It is very helpful to read this stuff; it makes me feel better about crawling into my warm bed instead of staying up late and cramming for a test!
ReplyDeletehttp://serendip.brynmawr.edu/bb/neuro/neuro03/web2/alippman.html
I completely agree with BrieAnna, I find myself struggling more with memorization for an exam when I stay up late studying and then wake up early before to study. Typically, this only ever allows me about four hours of sleep before each exam. I have definitely seen a difference in my performance level on these exams in comparison to last year when I received a full nights sleep. Further, as would be expected, with this "habit" of mine I have noticed an increased amount of anxiety pre-test and I know this affects how well I perform on that particular exam. A study printed in Sleep Medicine Reviews supports this "theory" of mine by finding that insufficient sleep or disrupted sleep can affect the systems that deal with other stressors and in the long run can become important risk factors that lead to stress-related disorders such as depression. So, needless to say, my study techniques have already changed since learning about this!
ReplyDeleteMeerlo, P., Sgoifo, A., & Suchecki, D. (2008). Restricted and disrupted sleep: Effects on autonomic function, neuroendocrine stress systems and stress responsivity. Sleep Medicine Reviews, 12(3), 197-210. doi:10.1016/j.smrv.2007.07.007
Thanks for the insightful post. Perhaps one of the reasons why the extra sleep did not effectively raise scores on the cognitive tests was because the extra two hours on the weekend (a total of 4 extra hours) did not equivalently replace the cumulative 10 hours of sleep time lost during the weekday (due to having 6 hours instead of 8). I actually don't believe that any equivalence in hours lost and gained would have any effect on the results, however, considering that increasing the hours gained in the weekend from 4 to 10 to offset losses would create a recovery sleep of at least 13 hours for each day; and as we probably know already from a prior blog post, oversleeping can contribute to loss of executive functioning.
ReplyDeleteWhile overloading on extra sleep time on the weekends won't work, what about trying to get a few naps during the daytime? According to a recent study, if a person were to take a nap after a cognitive test, they would retain a higher amount of the information as opposed to if they did not take a nap - and the longer the time spent in deep sleep, the more retention is increased. I can somewhat attest to this, as I've previously taken naps during the day to rejuvenate myself, and it makes me more energetic and focused; however, the amount of sleep is key, as too much can probably make you groggy.
http://www.scientificamerican.com/article.cfm?id=naps-for-better-recall