From time to time I read articles about sleep. A few years ago, European researchers found that people in pre-industrial times used to wake up for a while during the night, sleeping in two shifts. They would spend more time in bed, but often would not sleep the whole night through. It was thought that this was due, in part, to the long nights of winter in temperate and sub-arctic climates. Without artificial light there isn’t too much to do once it gets dark outside.

The generally accepted norm for sleep is seven to nine and a half hours. Some researchers have found that adults who get fewer than seven hours of sleep on average do not function at their best when they are awake. Those with not enough sleep have more difficulty concentrating and have more mood problems than those who average more than seven hours per night of sleep. Another study showed higher mortality rates among those who sleep fewer than seven hours per night. Less advertised was that the same study demonstrated that mortality rates also rise among those who sleep more than nine hours per night.

So how much sleep do we really need?

The National Sleep Foundation recognizes that sleep requirements decrease as we age. They recommend 14 to 17 hours per day for the first three months of life, decreasing to 12 - 15 hours in months 4 to 11. Toddlers and preschoolers continue to decrease in their sleep needs until at school age they do will with 9 - 11 hours of sleep per night. In our adult years, the foundation recommends 7 - 9 hours decreasing to 7 - 8 hours for adults 65 years and older. They also acknowledge that there are people whose sleep patterns vary and who function well and have good health with slightly less or slightly more than the averages.

That comes as a relief to me because I’ve been a pretty consistent 7 hours a night sleeper since my young adult years. I’ve never been a particularly good sleeper, waking easily and often rising for an hour or more to read in the middle of the night. I guess I have some of the genes from our pre-industrial ancestors.

I am, on the other hand, pretty good at taking naps. Although I don’t nap every day, when the opportunity presents itself, I can often be refreshed with a half hour to an hour’s sleep in the middle of the day.

Looking at the symptoms of those who receive too little sleep, it would seem that I am not deprived. I seem to be productive, happy and healthy during the day. Although I was a heavy coffee drinker in my young adult years, I have transitioned to a caffeine free lifestyle without any problems in alertness. I don’t fall asleep when driving or doing other tasks that require concentration and attention.

The one area that raises a bit of a red flag is that being overweight is associated with too little sleep and I have struggled with my weight for most of my adult life.

Enough about me, however.

A few days ago I read a new study by US-based researchers who studied the sleeping patterns of traditional hunter-gatherer societies in Africa and South America. They thought that studying traditional cultures living in relative isolation might give clues to the ways that our tribal ancestors lived. The study, published in the journal Current Biology, clearly illustrated that people in those societies do not sleep more than we do. In fact, they sleep less. 98 people were monitored for 1,165 nights. The study discovered that the average was 6.5 hours of sleep per night. Even more surprising was that sleep was not overly dependent on daylight. In the study, people fell asleep on average 3.3 hours after sunset. They gathered around fires, visited, ate, and engaged in other activities after the sun went down.

The study found that temperature was a more important factor in sleep than daylight. People in these traditional societies fall asleep in a time of falling temperature and when the temperature reaches its coldest point they tend to wake up.

Researchers also noted that insomnia was rare among the research subjects and that they rarely napped. When they did 25 minutes was the average length of nap time sleep.

I’m not sure that the study tells us anything about how our forebears lived. Comparing this recent study with earlier studies by European researchers, it seems to me that sleep patterns vary more by climate and location than by other factors. The fact that our sleep patterns are different than those of our ancestors doesn’t give much information about what is optimal for people living in our time and place. In terms of health, there are simply too many factors for a controlled study. It would appear that we sleep more than some of our ancestors and less than others.

In recent years the National Sleep Foundation has added a new range, “may be appropriate” to their sleep charts to illustrate that there are great differences in individuals when it comes to the amount of sleep needed.

So here is my new theory. Sleep when you are tired and get up when you aren’t sleeping. It seems to work for me. The best cure for insomnia that I’ve discovered so far is fatigue. If I engage in physical work for a day, I sleep well at night. When I have my exercise levels up, I am less likely to wake in the middle of the night. It sounds simple because it is.

I’m grateful to the researchers for all of their work, but I’m getting close to ignoring the studies when I read through the abstracts of current research. I’m not sure that we need more studies of how people sleep. More helpful for health and well being, it seems to me, is increase sensitivity to our own individual needs. Knowing what is average or normal doesn’t seem to be of much value if one doesn’t know what is right for him or her self.

As for me, well, I guess I’m neither a hunter/gatherer nor a pre-industrial ancestor. Life is far too interesting and exciting to spend too much of it in bed.

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