How Much Sleep Do You Need?
Rest is regeneration, where the body literally rebuilds most of itself within days. This idea is so new that people get very confused about how our regeneration works – or how much is needed. Sleep is the part of rest folks understand best, but how much sleep individuals need still creates bafflement and endless media commentary.
Sleep need is highly genetic. Some people can function well on 3 hours of sleep a night, while others need 9 hours. Most people “feel okay” with 7-8 hours of sleep, though studies argue they no longer know what full alertness is having grown so used to chronic sleep deprivation that it becomes the “new normal.” Yet when people sleep less or more than the 7-8 hours average figure, bad stuff tends to happen – probably because the rest-rebuild necessary for health is not working properly.
As can happen with stroke.
A recent study from my alma mater, the Harvard School of Public Health, was another follow-up of the longstanding Nurse’s study – in this example, nearly 70,000 nurses followed since the mid 1980’s. When controlling for different risk factors, nurses sleeping more than 9-10 hours had an increased stroke risk of 55%.
Long sleep has long been associated with greater cardiovascular risk. Is it because long sleep itself increase the risk of stroke and death, or is long sleep signaling that something else is going wrong?
Here are a few things to consider:
- This study was of nurses. Nurses do shift work. There is very good recent evidence that people with different genes, includes variants of the biological clock “period” and the DQ*1602 gene, prominent in narcoleptics, do poorly with shift work compared with the rest of the population.
- Shift work is itself a cardiovascular risk factor.
- When people are heavily stressed, they sleep less well, and then try to take more time for sleep.
- When people are getting sick – perhaps many years before they show clear clinical illness – they often show subtle physiologic changes that can include longer sleep times.
Sleep and Regeneration
Rest rebuilds the body. When the rebuild does not go right, whether for internal or external reasons (like infections,) illness occurs – whether it’s a cold, a broken Achilles tendon, or a tumor.
Yet much of what afflicts the population is chronic illness, where it takes years and years for the decline to be felt in the body’s ability to rebuild and regenerate itself (remember, you mostly get a new heart in three days.)
Nurses who sleep 9-10 hours per day are perhaps experiencing multiple physiologic difficulties. Some may have the mood and digestive changes brought by on shift work; others may have bodies that simply have a harder time dealing with the stresses of nursing – many of which take place not at work but at home. Long sleep may be one way the body tries to rebuild around those difficulties.
The Meaning of Long Sleep
Some of us need more or less sleep time for sleep’s brain and body renewing functions of sleep to work. But watch out when your sleep need markedly changes, especially for more than a few weeks.
When people become sick their regenerative capacity is compromised. Often they need to sleep more hours so that they will have more rest time to rebuild. Unfortunately, many illnesses prevent sleep. That may explain why both long and short sleepers show higher death rates in most international studies.
So if your sleep time changes markedly, ask why. Is it work? Is it social engagements, as so often afflicts the young?
Or is it something – else? Perhaps your body is telling you need more rest. Though rebuilding in our body is enormously fast, there is so much to do that it takes time – more when you’re ill or trying to prevent illness.
So it pays to always listen to your body. Then do what makes sense – what your body is designed to do. When you need more rest, the best plan is to get it.
It’s not a waste of time. Rest renews you. And when you’re sick you need to rest more.
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