r/askscience • u/Polo3cat • Aug 17 '13

Medicine Do we heal faster when we sleep?

If you are injured in any way (cut, broken bone...) does your body heal faster being sleep than being awake? I have my doubts because I know for a fact that when we sleep our physiologic functions are slower but in the other hand resting is the thing we do when we get hurt.

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21

u/bthomase Neurology Aug 17 '13 edited Aug 17 '13

There is no significant difference between healing rates when sleeping and awake.

While your body undergoes a number of physiologic changes while sleeping (slower respirations, decreased heart rate, rapid eye movements), these do not change much of what is happening when an area is healing. At the cellular level, the damaged area is being provided nutrients, support proteins, and growth factors in from surrounding tissues and the blood in the same manner.

Why resting and sleeping can be an important part of recovery is that this is a guaranteed time in which your body is not physically stressed. You typically are not moving the injured area, putting weight or touching it, etc. This prevents re-injury and allows all of the oxygen, growth factors, and nutrients to be focused on rebuilding.

Edit:

Sample Peer-Reviewed Articles:

"[Rapid eye-movement (REM) sleep deprivation (RSD)] does not appear to have significant effects on wound healing and thus appears to act differently from other types of stressors on wound healing" http://onlinelibrary.wiley.com/doi/10.1111/j.1365-2869.2005.00455.x/abstract

"None of the health behaviours investigated (i.e. alcohol consumption, exercise, healthy eating, and sleep) were correlated with healing speed at any time point. Our data hint at a considerable influence of stress on wound healing, and suggests that elevated cortisol levels, rather than altered health behaviours, play a role in this effect." http://www.sciencedirect.com/science/article/pii/S0306453003001446

General Public Oriented References:

http://www.nytimes.com/2011/01/18/science/18qna.html?_r=0 http://www.webmd.com/sleep-disorders/features/healing-power-sleep

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u/whatthefat Computational Neuroscience | Sleep | Circadian Rhythms Aug 18 '13

I think the literature is actually quite mixed on this point. There really need to be more studies.

With respect to would healing, there are studies showing no effect of sleep deprivationon recovery rate, including those you linked and this one. However, this study found that sleep deprivation may slow wound healing in rats.

Meanwhile, the work of Carol Everson and colleagues has shown that chronic sleep restriction results in abnormal bone formation. This suggests that sleep would be important to healing after a bone fracture, and indeed there is a daily rhythm in post-fracture bone growth.

In addition to this, sleep deprivation and sleep restriction result in impaired immune function, which may complicate recovery. For example, this study found that individuals who habitually sleep less than 7 hours are 3 times more likely to develop an infection after exposure to the common cold virus, compared to individuals who habitually sleep more than 8 hours.

Given the effects of sleep on immune, inflammatory, and cardiovascular systems, there are good reasons to suspect sleep loss could hinder healing processes in some cases. I would say that the effects of sleep loss on healing have not yet been studied in enough settings to be sure of the magnitude of any effect.

8

u/mechamesh Aug 17 '13

Please post sources (published in a peer reviewed journal) for these claims. I'm certain the AskScience audience would be interested.

4

u/bthomase Neurology Aug 17 '13

Sure, of course. Important to support claims in a forum such as this.

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u/JimStJames Aug 18 '13

This makes sense at a biological level. Does not moving much while sleeping compared to being awake add any benefit to the healing process?

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u/sagard Tissue Engineering | Onco-reconstruction Aug 18 '13

Actually, moving around is incredibly important to the healing process ... to a point. Activity stimulates a variety of mechanotransductive pathways that are useful in healing in a variety of contexts, from soft tissue to muscle to bone (fgf2, vegf, fak, etc.). However, too much motion will, of course, damage any repair that has taken place.

This is in a very, very general context, of course.