When it comes to health & fitness, diet & exercise are king. Over the past 25 days I have worked diligently at refining my diet & exercise program to maximize the progress I’m making both in the gym & on the trails. One important area of fitness that is often overlooked, & where I have certainly fallen short over the first 25 days, is sleep.
Many of us have
this idea ingrained that sleep is for the weak; we celebrate those who are early to rise
& stay up late grinding to get a job done. Phrases such as 'I can sleep when I'm dead,' & 'Sleep is for the weak' have permeated mainstream lexicon. In our busy culture, we've come to celebrate those who can operate on little sleep & vilify those who prioritize a good nights' sleep as lazy, or unmotivated. In this post, I focus on the role that sleep plays on athletic performance & muscle recovery to determine once & for all how important getting 8 hours really is.
My Sleep Schedule
First, I want to give a quick background of my sleep schedule. I am an early riser. I love being up before everyone else. I subscribe heavily to the Floyd Mayweather mantra of "while you're working I'm working. While you're sleeping, I'm working." Since January 1st I have woken up every weekday at 4:30, despite not having to be at work until 8:00. I love getting up, having a coffee, meditating, reading, & more recently, researching for, & writing blog posts. I find this is the time when my brain in the sharpest & when I have the most focus.
What I have not considered until recently, is that perhaps the reason I am sharpest first thing in the morning is because the rest of the day, my body & mind are exhausted from lack of sleep! Right now, I am typically getting to bed around 11:30 & waking up at 4:30, meaning I’m getting 5 hours of sleep at most! Throw in a late night or a little bit of difficulty getting to sleep, & I’m quickly below 5 hours of sleep.
My Sleep Schedule
First, I want to give a quick background of my sleep schedule. I am an early riser. I love being up before everyone else. I subscribe heavily to the Floyd Mayweather mantra of "while you're working I'm working. While you're sleeping, I'm working." Since January 1st I have woken up every weekday at 4:30, despite not having to be at work until 8:00. I love getting up, having a coffee, meditating, reading, & more recently, researching for, & writing blog posts. I find this is the time when my brain in the sharpest & when I have the most focus.
What I have not considered until recently, is that perhaps the reason I am sharpest first thing in the morning is because the rest of the day, my body & mind are exhausted from lack of sleep! Right now, I am typically getting to bed around 11:30 & waking up at 4:30, meaning I’m getting 5 hours of sleep at most! Throw in a late night or a little bit of difficulty getting to sleep, & I’m quickly below 5 hours of sleep.
Why Is Sleep Important?
Prior to researching this post, I had blinders on regarding the impact of sleep on athletic performance & recovery. While researching for my post on recovery, I came across a few studies focusing on the role of sleep in muscular recovery, however since the studies did not draw hard-line, quantitative conclusions, I did not internalize them in the same way as the research on saunas, or nutrition, both of which I have discussed at length in previous blog posts.
A quick Google search on the importance of sleep brings up a 2011 Pubmed study that states, 'Sleep is essential for the cellular, organic &
systemic functions of an organism, with its absence being potentially harmful
to health & changing feeding behaviour, glucose regulation, blood pressure,
cognitive processes & some hormonal changes.' This makes intuitive sense, everyone has experienced the cognitive 'fog' & increased stress that occurs from being tired, but what about athletic performance?
For those training for a Spartan Race, the study goes on to hypothesize that 'sleep debt decreases the activity of protein synthesis pathways and
increases the activity of degradation pathways, favoring the loss of
muscle mass and thus hindering muscle recovery after damage induced by
exercise.'
Obviously loss of muscle mass & hindrance of muscle recovery is problematic for those of us putting our bodies through the rigors of Spartan Race training. What this second point suggests is that by training hard & not getting adequate sleep, you could be simply degrading your muscles. This is certainly problematic, but the question remains how much sleep do we need to fully recover our muscles & how much is ancillary?
The '4.5 Hour Baseline'
According to a
1999 study by J.A. Horne, it was suggested that only 4.5 hours of sleep, referred
to as ‘core sleep requirements,’ were needed to ‘satisfy the brain’s physiological
need for recuperation & any sleep in excess of this is
essentially appetitive,' or supplementary.
This research fits in well with my current sleep pattern & is a positive sign
for those of us that tend to operate in a more sleep-deprived state.The '4.5 Hour Baseline'
In a more recent study however, subjects were tested by sleeping for 3, 5, 7, & 9 per night over a 7-day period, then tested on speed & cognitive performance (reaction time). The study noted that speed & cognitive performance dipped from baseline levels for those getting 3, 5, & 7 hours of sleep per night, while the performance of those getting 9 hours of sleep per night stayed at baseline, suggesting that running a ‘sleep deficit’ can have a significant impact on speed & reaction time, two important metrics related to athletic performance.
Further, although the
performance of subjects getting 5 & 7 hours per night stabilized after an initial drop off, their performance in both speed & reaction time remained below original baseline levels, suggesting an enduring negative
impact on athletic & cognitive performance. Further, for those getting 3
hours per night, the subjects performance continued to degrade over time for each of the 7 days.
The conclusion here is that although performance will normalize at 4.5 to 5 hours of sleep per night, the normalization will occur at sub-optimal levels in terms of speed & reaction time. So although performance will not continue to degrade once the new baseline is established, it is not at optimal performance levels which shows that sleep beyond the core requirements produces correspondingly
higher & stable levels of alertness & performance
'Catching Up' On Sleep
A common strategy employed from those of us with a Monday to Friday work schedule is to 'catch up' on the weekends, meaning running on mild or extreme sleep deprivation from Monday to Friday, then 'catching up' by sleeping for 10 hours or more on weekends. Unfortunately it seems that the effects of sleep deprivation cannot be overcome by just a few days of 'proper' amounts of sleep.
In the study where speed & reaction time were measured in subjects sleeping for 3, 5, & 7 hours per night, it was shown that performance did not return to baseline levels even after 3 days of 8-hours sleep cycles, suggesting that prolonged sleep deprivation prevents rapid return to baseline performance. Fortunately, other studies have shown that acute sleep deprivation (ie. one night’s poor sleep) has a rapid recovery to baseline performance after a single nights sleep.
In the study where speed & reaction time were measured in subjects sleeping for 3, 5, & 7 hours per night, it was shown that performance did not return to baseline levels even after 3 days of 8-hours sleep cycles, suggesting that prolonged sleep deprivation prevents rapid return to baseline performance. Fortunately, other studies have shown that acute sleep deprivation (ie. one night’s poor sleep) has a rapid recovery to baseline performance after a single nights sleep.
Combined, these studies suggest that it is long-term, even partial sleep-deprivation that has a more profound impact on cognitive & athletic performance as opposed to acute, one-time occurrences of sleep deprivation. Thus, the age old strategy of 'catching up on sleep' appears to not overcome the negative consequences of prolonged sleep deprivation.
Quantitative Impact of Sleep Deprivation
Despite the research above suggesting that sleep deprivation negatively impacts athletic performance, I am a very quantitative-minded person. I need to know how much sleep deprivation impacts athletic performance, yet the majority of research tends to focus on cognitive as opposed to physical performance, or looks at the results on athletic performance qualitatively as opposed to quantitatively.
Fortunately for my quantitative mind, one often-cited study showed that, during prolonged treadmill walking, sleep-deprived subjects demonstrated reduced work time to exhaustion by an average of 11%. Although this result seems convincing that sleep deprivation reduces athletic performance, the study also showed that exercise heart rate & metabolic rate were unchanged in those who were sleep deprived, & the study cited a significant increase in perceived exertion as the mechanism for the decreased performance. Of course they have to add a qualitative aspect to this quantitative study!
Fortunately for my quantitative mind, one often-cited study showed that, during prolonged treadmill walking, sleep-deprived subjects demonstrated reduced work time to exhaustion by an average of 11%. Although this result seems convincing that sleep deprivation reduces athletic performance, the study also showed that exercise heart rate & metabolic rate were unchanged in those who were sleep deprived, & the study cited a significant increase in perceived exertion as the mechanism for the decreased performance. Of course they have to add a qualitative aspect to this quantitative study!
Therefore although athletic performance has been repeatedly shown to be reduced in different sport-specific studies,
the mechanism for the decreased performance is still unclear, & it
may not be a physiological trigger, but instead a psychological trigger
that causes sleep-deprived athletes to perform poorer relative to their
well-rested counterparts.
Future Sleeping Plan
Future Sleeping Plan
So after all of
that research, how do I plan to alter my current sleep schedule? For me the
research is somewhat conflicting. As with most research related to athletic
performance, evidence suggests that there is a sliding scale regarding the
impacts of sleep deprivation.
On one hand, you
have the ‘critical sleep requirement’ research that suggests you can maintain a
baseline of athletic performance at 4.5 hours of sleep per night, yet you have
other studies that have shown that, although the body does establish a baseline
of performance at this small amount of sleep, this baseline is clearly at a
diminished level from the baseline of 8 hours. The question remains; what is that
delta between baseline at 4.5 hours & baseline at 8 hours?
For me, it is a matter of personal experimentation. For the next week, I am going to be sleeping from 10PM (1 hour earlier than usual) until 6AM (1.5 hours later than usual). I am committed to follow this training plan for 7 days, & see how it effects my body. What has become clear to me after conducting this research, is that sleep is clearly important, but how much is up to the individual.
Although I would have loved to be able to conclude this post with ‘you must sleep 8 hours or performance will be negatively effected 20%,’ the reality is that the research is not as cut & dry. For me, my main takeaway is that you must do some personal experimentation to determine what is the optimal level for you personally.
For me, it is a matter of personal experimentation. For the next week, I am going to be sleeping from 10PM (1 hour earlier than usual) until 6AM (1.5 hours later than usual). I am committed to follow this training plan for 7 days, & see how it effects my body. What has become clear to me after conducting this research, is that sleep is clearly important, but how much is up to the individual.
Although I would have loved to be able to conclude this post with ‘you must sleep 8 hours or performance will be negatively effected 20%,’ the reality is that the research is not as cut & dry. For me, my main takeaway is that you must do some personal experimentation to determine what is the optimal level for you personally.
100 Day Spartan
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