As a society, we are just plain tired. We are overscheduled and overworked, and sleep has become less and less of a priority. Adding insult to injury, an estimated 40 million Americans suffer from chronic, long-term sleep disorders, while another 20 million experience occasional sleep problems. Is it any wonder so many of us feel like walking dead?
Unfortunately, this serious lack of shut-eye has greater repercussions beyond just leaving us tired and craving more caffeine. Too little sleep has been linked to several diseases and health problems, including stroke, cancer, heart conditions, obesity and even memory issues.
And now, a recent meta-analysis confirms that too short and, interestingly, too long sleep durations can be blamed for hypertension (otherwise known as high blood pressure), as well.
Researchers looked at 23 studies that used either a cross-sectional, case-control or cohort design and evaluated the connection between both short and long sleep durations and hypertension.
The studies varied on how they defined short sleep duration, with it ranging from less than five hours to less than seven hours, while long duration of sleep was defined as more than nine hours in some studies, and 10-15 hours per night in others.
Shorter Sleep Duration
Six prospective studies involving almost 10,000 participants were included, and the results suggested a link between short sleep duration and the risk of hypertension among people younger than 65, but not among those older than 65.
In the 17 cross-sectional studies they examined, which included a total of 105,432 participants, researchers determined a much stronger connection between shorter sleep duration and hypertension. When analyzed by age, researchers found that those younger than 65 had a significantly higher hypertension risk with shorter sleep durations. Those older than 65, however, did not have a higher risk. When divided by sex, women had a higher risk of hypertension with shorter sleep times.
Longer Sleep Duration
When looking at long sleep durations and hypertension risk, researchers noticed that, overall, there was a significant association between long sleep duration and hypertension, as well.
In 13 cross-sectional studies involving 90,356 participants, researchers noted a significant association between longer sleep duration and the prevalence of hypertension. This risk was higher in participants younger than 65.
Making Sense of These Conclusions
Looking at these results, you would think that you just can’t win. You sleep too little, and you put yourself at risk. You sleep too much, and you also put yourself at risk.
In the case of too little sleep, the increased risk of hypertension makes sense. As mentioned earlier, research has shown connections between too little sleep and numerous health conditions.
Some research has shown that lack of sleep could mess with hormone levels in the body, leading to increased cortisol levels, renal impairment, endothelial dysfunction and inflammation, all of which contribute to hypertension.
In addition, getting too little sleep often is usually associated with irritability, impatience, pessimism and stress, which could make it more difficult to live the healthy style necessary to avoid hypertension.
As for longer sleep durations and risk for hypertension, researchers point to one condition that could link the two together — sleep apnea. Those with sleep apnea tend to spend more time sleeping due to the fragmented nature of their slumber. And research has already established a link between sleep apnea and hypertension, as well as other heart problems.
Other factors that researchers mentioned could link long sleep duration with hypertension include depression, unemployment, being single, and low socioeconomic status. However, they note that there is no definitive causative risk factor that makes getting more than nine hours of sleep harmful, so further research obviously needs to be conducted in this area.
The fact clearly remains, though, that getting too little sleep is a scientifically proven problem — much more so than getting too much sleep.
How Much Sleep is Right for You?
Only you know how much sleep is optimal for you, and your needs will vary based on your age and stage in life. According to the National Sleep Foundation, most adults need anywhere from seven to nine hours of sleep per night, while children need significantly more.
Pay attention to how you feel on different amounts of sleep. If you feel like you need a constant supply of caffeine to get you through the day on seven hours of sleep, then you need more. If you are happier, more energetic, and more productive with eight hours of sleep, then you’ve found your magic number.
 Wang Q et al. Short sleep duration is associated with hypertension risk among adults: a systematic review and meta-analysis. Hypertens Res. 2012 Oct;35(10):1012-8.