In February the National Sleep Foundation announced the publication of new guidelines for the amount of sleep that we should be getting based on a rigorous review of the literature.
The guidelines suggested that adults should be getting between seven and nine hours of sleep.
The results were widely distributed and commented on. It was noted that many people in our increasingly “tech crazy” society were not getting as much sleep as they needed. As we have noted elsewhere, inadequate sleep may be associated with significant negative effects on brain function.
The study Chair summarized the process that led to the guidelines being issued:
“The NSF has committed to regularly reviewing and providing scientifically rigorous recommendations,” says Max Hirshkowitz, PhD, Chair of the National Sleep Foundation Scientific Advisory Council. “The public can be confident that these recommendations represent the best guidance for sleep duration and health.”
Many of us felt troubled. Should we take a sleep medication if we couldn’t get that much sleep?
I have long been skeptical about some of these suggestions, in particular the idea that getting more than 8 1/2 hours of sleep is healthy. In my experience, those who are sleeping more than that are likely to feel more fatigued rather than less fatigued. This belief is bolstered by the results of the largest study that looked at health correlates of different amounts of sleep. That study (by Daniel Kripke – see below) found that sleeping more than 8 1/2 hours was associated with poorer health than sleeping between 6 1/2 and seven hours at night.
Some sleep experts have speculated that before the development of artificial illumination, it was common for people to fall asleep within an hour or so of the sun setting. This would have resulted in very long periods of sleep in the winter in much of the globe.
A new study examined sleep in three hunter gatherer societies located around the world and found that our ancestors did not sleep that much differently from how we sleep today in modern society.
- Preindustrial societies in Tanzania, Namibia, and Bolivia show similar sleep parameters.
- They do not sleep more than ‘‘modern’’ humans, with average durations of 5.7–7.1 hr.
- They go to sleep several hours after sunset and typically awaken before sunrise.
- Temperature appears to be a major regulator of human sleep duration and timing.
In the New York Times article that summarized the study one sleep researcher had this to say about the finding –
“I think this paper is going to transform the field of sleep,” said John Peever, a sleep expert at the University of Toronto who was not involved in the new research. “It’s difficult to envision how we can claim that Western society is highly sleep deprived if these groups that live without all these modern distractions and pressing schedules sleep less or about the same amount as the average Joe does here in North America.”
I was fascinated by one of the findings, which was quite surprising, whereas sleep onset was quite variable with some people falling asleep within an hour of sunset and others staying awake for three or four hours, when people woke up from sleep was consistent across all three tribes.
People wake up at the point in the night when outside temperature stops falling. Or to put it another way, they wake up when the temperature starts to go up.
Here is an opportunity for Nest and other manufacturers of fancy thermostats for the home – develop an algorithm that gradually lowers temperature throughout the night and starts to raise it at the point when people want to wake up.
Combining this with light exposure may give us a lot more effective solutions for insomnia than the sleep medications that so many of us take at night. And without the side effects.
Kripke DF, Garfinkel L, Wingard DL, Klauber MR, Marler MR. Mortality associated with sleep duration and insomnia. Arch Gen Psychiatry. 2002 Feb;59(2):131-6. PubMed PMID: 11825133.