How much sleep do runners really need? Me? I'm a 8-hours-a-day kinda girl under the best of circumstances. Once I start kicking up the volume and hitting 50, 60....70 miles a week, I like to sneak in a little more than that even. The fact is though, lately, I just haven't been getting it. There's a concert that I want to go to, my friends are meeting for dinner, I've got a new boyfriend that I want to hang with, I should be updating my resume, I need to edit those photos for my cousin, I need to do the laundry...there's always something to justify pushing my bedtime later and later. At the same time I've been getting up earlier to beat the heat and get my runs in before work in the morning. Add in a little bit of stress and anxiety about my career stagnation and job interview rejections and before you know it, there's a little insomnia in the mix as well. Last night was just six hours long for me, which is okay once in a while, but it's been happening more and more frequently of late.
There's an Australian study (Griffin, S.J. and Trinder, J. (1978). Physical fitness, exercise and human sleep), that compared 45 mile/week runners with serious weight lifters and sedentary people and of the three groups, the runners fell asleep more quickly and slept the longest and deepest. That's only one study, but it does seem to be commonly accepted that exercise helps you sleep. Of course, you actually have to lie down and shut your eyes at some point to get that benefit. It's obviously much less effective when you're still wide awake in a wine bar with your college buddies at 1 am. Ironically, one of the symptoms of overtraining is insomnia, so I guess the positive effects of exercise on the sleep cycle are not without their limits.
I've just been thinking about this a lot because I'm really not running that much mileage these days, about 40 miles/week now, and I've been feeling really fatigued. The marathon was two months ago now, so I really think it has to do more with the career anxiety and the hours I've been shaving off my sleep cycle.
I read about another study, this one in the Lancet, that went more into the why of it all. The researchers figured out that even just a few days of mild sleep deprivation interfered with glucose metabolism and raised cortisol levels. That's that nasty hormone that those Cortislim info-mercials insist will make us fat, but according to these scientists, it also messes with athletic recovery. It also turns out that it's in our deepest continuous sleep that the body produces the highest levels of human growth hormone, which is such good stuff and so important to athletic performance and recovery that it's considered illegal to supplement it in Olympic sports and in most professional sports. It also is a frequent subject of the spam in my e-mail in-box every morning. And all I have to do is sleep more to make this stuff? Get me my pillow already!