A circadian, solstice-centric sleep schedule
8/31/07
There is little doubt that modern life disconnects us with the natural cycle of day and night. Light bulbs, monitors, TVs, and even curtains all conspire to give us the power to choose the brightness in our lives. And generally, we do the opposite of what nature intends. Research has noted that the average American gets only about 30 minutes of direct sunlight (over 1000 lux) per day. So paradoxically, we get less sunlight than our Neanderthal ancestors, and yet also less darkness.
Our energy levels and our sleepiness follow a rhythm based on, among other things, the amount of light we see. Therefore, we’re less awake during the day, and less sleepy during the night, and in order to reconnect ourselves to the rhythms of the day, we need to better understand how that connection occurs.
What is the rhythmic connection between the world and our bodies? Externally, there are quite a few: light, temperature, social interaction, and eating and drinking schedules. These synchronizing agents are called Zietgebers (German for “Time Givers”), of which light has the strongest effect our own bodily rhythms. (Obviously, all the Zietgebers listed above are correlated.) Since light is the strongest Zietgeber, the actual connection between the world and our bodies comes most strongly from our eyes. Our retinas pick up the light, which travels through the optic nerve into suprachiasmatic nucleus (SCN) region of our hypothalamus.
What functions to our bodies perform based on these signals? The three most pertinent are body temperature, heart rate, and blood pressure are the most clear.
So, what would be the most natural sleep pattern? Since humans sleep when it’s dark, the most sensible sleep schedule should maximize the percent of sleep done in the dark.
To calculate this, one must figure out what I call the “solar noon” (middle of the day) and “solar midnight” (middle of the night). Interestingly, neither change that much. The changes in sunrise and sunset are close to symmetrical. Just find the time midway between sunset and sunrise.
Next, one should figure out how much sleep one needs. Be generous. For this analysis, I assume that I need 8 hours. For this example, once you have those stats, find the solar midnight, and go to bed 4 hours before then and get up 4 hours after then.
To figure out your particular location’s sunrise and sunset, just search on the internet. I’d recommend starting with just the summer and winter solstices, June 21 and December 21. From there, you’ll be able calculate the “solar noon” and more importantly “solar midnight”, around which you’ll figure out your own custom sleep schedule. Later you can fill in the days between the solstices.
Obviously, times will vary based on your geographic latitude. Here’s some figures for New York City:
ANALYSIS OF OPTIMAL SLEEP BASED ON THE SOLSTICE
June 21: Sunrise at 5:24am, sunset at 20:30. Thus, solar midnight is 0:58.
December 21: Sunrise at 7:16am, sunset at 16:31. Thus, solar midnight is 23:58.
Data From:
http://www.geocities.com/dtmcbride/science/astronomy/sunrise_sunset.html
The data above show that, in the summer, I’d need to go to bed around 9pm and get up around 5am, which in the winter I should go to bed around 8pm and rise at 4am. For most people, these times seem quote earlier than typical. It seems that modern society has us off kilter by an hour or two, and often far more. Consider that this schedule maximizes the percent of amount of darkness you’ll experience while sleeping, and the amount of light you’ll experience while awake. There are massive environmental and cost saving benefits as well, but they are beyond this article’s scope.
I have been using the schedule (roughly) for nearly a year, and having improved my sleep quality, decreased the amount of sleep I need, and experienced higher mental acuity during the day. Lastly, I feel a more regular connection to nature that provides solace in a world increasingly ignorant of nature’s wisdom.