Is broken sleep worse than a short sleep duration?
There is some controversy among sleep researchers about whether sleeping less than seven hours a night actually puts a person at risk for disease or not. Michael Irwin, M.D. of UCLA is one researcher who questions the cause and effect between short sleep duration and increased risk of disease.
Sleep Studies
At the 2016 Sleep Meeting in June he reported that, after a review of 73 sleep studies, both self-reported and objectively measured sleep duration of less than seven hours was not associated with the inflammatory markers C-Reactive Protein (CRP), Interleukin-6 and Interleukin-8, all variables partially responsible for diseases such as diabetes, rheumatoid arthritis, and heart disease.
If we take a closer look at these myriad studies, however, we see that short sleep duration is, in fact, associated with other markers that may indicate poor health. These more sensitive markers show an increase in signaling pathways for inflammation and an increase in cellular production for inflammation.
What this means is that, as Carol Everson stated at the 2015 Sleep Meeting “lack of sleep can be a silent killer” as these inflammatory markers are so sensitive they will not be detected on regular blood tests. In addition, most of these studies did not look at chronic sleep duration shorter than six hours, a number that many researchers say is really the culprit when it comes to disease.
Furthermore, Irwin discovered that long sleep duration (that is greater than 8 hours of sleep a night in an adult population) positively impacted inflammation. In other words, sleeping too much seems to cause more inflammation in the body than sleeping too little. In fact, Irwin’s research indicated that long sleepers have a 30% increased risk of morbidity! That tidbit makes you want to set an alarm after all.
Impact of Broken Sleep
The other significant finding in this overview of the research, is that self-reported sleep disturbance was associated with elevated CRP and Interlukin-6.
Why the difference between sleep disturbance and sleep duration? One can speculate that with short sleep duration (for example 6.5 hours of sleep a night) a person is getting good quality sleep.
If a sleeper is sleeping through the night on these 6.5 hours, then he or she is benefiting from the full 90-minute sleep cycles we need in order to dream and in order to achieve deep sleep. If, however, the next sleeper is obtaining 7.5 hours or sleep a night, but it is fitful sleep (i.e., the person wakes easily and frequently) then he or she isn’t getting the kind of deep sleep the body and brain need to restore themselves for optimal functioning.
Scientists call this “sleep fragmentation” and it appears, according to Irwin, that this is the more disturbing circumstance when it comes to the associations between sleep and poor health.
Did You Sleep Well?
I know that in my own life if my husband asks how many hours of sleep I got the night before, unless it is an extremely low number, the question seems somewhat irrelevant.What matters to me is if I slept well, not long. That is, if I feel refreshed in the morning I believe I got a good night’s sleep, even if it was only 6 hours.
This notion is supported by Jerry Siegel’s research with hunter/gatherer populations living in primitive (natural) environments in the jungles of Bolivia, Namibia and Tanzania.
Across these three groups there seemed to be an average sleep duration of 6.5 hours per night with no middle of the night wakings of any significance. These groups were deemed generally healthy. In fact, a separate NIH study of the health of the Tsimane people in Bolivia indicated that poor health manifested most in their child morbidity rate due to lack of immunizations with no indication of disease we most commonly see in the U.S., such as heart disease and autoimmune disease—both influenced by inflammation.
Broken Sleep: The Impact of Stress
Another way to look at this is to examine the impact of stress on the body’s inflammatory markers. There has been plentiful research on the fact that anxiety and depressive disorders are associated with an elevation in C-Reactive Protein (Copeland, William et.al, Psych Med 2012 Dec: 42(12).) Many people with sleep disturbance are anxious and/or depressed, hyperarousal being one of the predictors of insomnia.
It is very possible that what we thought was a cause and effect relationship between little sleep and disease is really a relationship between psychological stress and disease, with sleep disturbance as a symptom that goes with the territory.
Broken Sleep: Conclusion
In other words, people who struggle with sleep are generally more stressed and this overall stress, whether experienced during the day or at night, may be the more significant factor in increasing inflammatory markers.
I’m not saying that sleep loss isn’t a big deal. I can tell you first hand it is. What I am saying is that treating our stress levels may be just, if not more, crucial than going after sleep disturbance first. In other words, you may want to emphasize vacation and meditation and worry less about that Ambien refill.
