Circadian Rhythms

Articles

Does Dim Light at Night Make You Fat?

Before electricity, humans got all of their light via exposure to the sun, fire, and the moon and stars. This meant that nights were spent in relative darkness. Today, our environment is quite different. Our homes can now be brightly illuminated all the time, regardless of season or time of day. Also, our cities have bright LED street lamps that create “light pollution” filling outdoor city environments with much more light than is natural.

On the latest episode of humanOS Radio, I talk to Dr. Laura Fonken who is postdoctoral fellow in Steven Maier’s lab in the Department of Psychology and Neuroscience at the University of Colorado. Before joining the Maier lab, she and a group at Ohio State performed a fascinating experiment with rodents, in which they compared body weight gain in animals who only ate at night versus animals who only ate during the day. The results were startling – and had interesting potential implications for our own health.

Check out our interview here to learn more!


A New Product to Significantly Reduce Jet Lag – Interview with Stanford Professor, Jamie Zeitzer

In Professor Jamie Zietzer’s recent research on light and the timing of biological rhythms, he noticed something curious: brief flashes of light have a greater ability to adjust body clock timing than continuous light exposure.

For instance, let’s say you wanted to adjust your body clock to wake up earlier than you typically do in the coming days (a common scenario for those who travel across time zones). In order to make this adjustment, on the morning before you leave, you could wake up at 4:00am, turn on the room light and go back to sleep. This technique can adjust your clock by about 35 minutes, which means that if you typically awake at 7:30am, you could naturally wake up tomorrow around 6:55am (and the timing of all your other body processes would shift accordingly, too).

On the other hand, if you were to get 2 millisecond flash of light every 10 seconds starting at 4:00am (instead of laying in a room with the light on) – something Jamie’s research has demonstrated you can sleep through – you could advance your clock by about 120 minutes – over 3x more than continuous light.

What does this mean? Well, one thing it means is that it would be a heck of a lot easier to be up and ready before your typical natural wake time in those moments when you have an early start to your day (e.g., early plane flight). The ability to affect your body timing in this manner is more than a mere luxury; it’s also about personal safety and performance. None of us want to be on the road with sleepy drivers, and likewise, no one wants to have to perform at a time when you’re too sleepy to keep your eyes open. This is pretty exciting technology!


Research Reveals a Surprising Link Between Melatonin and Type 2 Diabetes

We typically associate the hormone melatonin with sleep. However, melatonin is actually involved in the timing and synchronization of a number of different physiological functions throughout the body. One of these functions is the regulation of blood sugar.

Recent research has found that a relatively large proportion of the human population is genetically predisposed to be more sensitive to the impact of this hormone on blood sugar control. This can lead to higher blood glucose levels, and ultimately greater risk of developing type 2 diabetes.

Here’s how it works, and what you can do about it.


Certain Dietary Fats Disrupt the Coordination of Metabolism, Others Don’t

When the system in our body that controls the timing of our physiology becomes uncoordinated or misaligned, bad things happen. This can happen in several ways.

The most well-understood way is due to big fluctuations in the timing light exposure from day to day. This is why Apple recently introduce night shift to help limit the impact cell phones can contribute to this issue. But big fluctuations in the timing of light exposure is not the only way to misalign our rhythms. The type and timing of dietary fat also impact’s this system.


When Is the Best Time to Eat?

Around this time of year, much of the world is advancing their clocks by one hour to make efficient use of seasonal daylight. Americans switched to Daylight Savings Time last week, and this week Europeans will revert to Summer Time.

When this happens, we all “lose” an hour of sleep, because we have to get up and get things done an hour earlier than we have been. This is in relation not just to the light and dark cycles of the day, but also to our body clocks.

One hour sounds like a small change, but it can make a big difference in how we function, at least in the short term. For example, data from the past two decades shows that there is a statistically significant spike in the number of car wrecks on the Monday immediately following the shift to Daylight Savings Time in the US.

As we all adjust to the time change, it’s worthwhile to consider how other aspects of our lives can sway our circadian rhythms. Circadian clocks govern the rhythms of sleep and activity in virtually all animals and are responsive to a variety of stimuli like light and stress. Research is starting to suggest that our eating patterns – specifically when we eat – can also have a pervasive impact.


The Freakonomics of Sleep (Part 1)

Back in May of this year, I give a presentation entitled Sleep, Productivity, and Peak Performance at a CEO summit in Manhattan hosted by VC firm, Firstmark Capital. After I presented, Steven Dubner of Freakonomics spoke about the man who smashed the world record at Nathan’s hot dog eating contest. See more about this story in the blog post. After we both presented, Dubner approached me for an interview to discuss sleep. My interview was included in the two-part series that they just published on the subject.



What Your Doctor Isn’t Thinking About (Dragging Medical Professionals Into the Modern Era)

The other day I came across this alarming video of what it’s like to drive in Poland. My first thought after watching the clip was “What’s the Toxoplasmosis gondii infection rate in Poland?” T. gondii is a brain parasite easily acquired from eating undercooked meat, or contact with cats, and is associated with a six-fold increase in traffic accidents (this association has been replicated a number of times, in different countries). Well, I looked it up, and found that the latent infection rate in 2003 was around 41% (at least among pregnant women). That’s quite high — in the U.S. the infection rate is only about 11%.

Is there anything to my hypothesis that terrible driving in Poland is related to the relatively high T. gondii infection rate? Probably not. The accident fatality rate in Poland is relatively high for a modern industrialized country. But France has a very low accident fatality rate, and a much higher rate of T. gondii infection. So while T. gondii might be a contributing factor, it’s probably not the most important variable.

I’m fascinated by latent/chronic biological infections, and how they affect human health and behavior. T. gondii in particular is linked to changes in personality, and even schizophrenia.