Sleep is important for health and weight. Sleep, like many other processes, is governed by the Brain. In particular, the brain contains a “clock” that resides primarily in the suprachiasmatic nucleus (SCN). This clock has a cycle of approximately 24 hours, and regulates other parts of the brain that effect the onset and termination of sleep. The SCN is a tiny nucleus that’s positioned just above the optic chiasm, the place where the two optic nerves cross. These are the nerves that transmit information from the retinas to the brain. Not surprisingly, the SCN receives direct input from the retinas. Also not surprisingly for a species that lives by the day-night cycle, the human SCN clock is set primarily by light.
This poses a problem for modern humans, who expose ourselves to artificial light long after the sun has gone down. This light essentially tells our SCN clock it’s still daytime, making it more difficult to sleep at night and more difficult to get up in the morning. This is clearly evident because nighttime light suppresses the secretion of the sleep hormone melatonin by the pineal gland, which is under the control of the SCN (1, 2).
Interestingly, the photoreceptors in the retina that project to the SCN are most sensitive to blue light (1, 2). This may be because midday sunlight is more blue than light around sunrise and sunset, and is therefore a better cue for setting the clock. In any case, this peculiarity of human physiology gives us the opportunity to minimize the negative impacts of evening light by shifting it to a less blue spectrum.
Computer monitors are one of the most problematic sources of light because they’re bright and often contain a lot of blue light. One solution is to wear blue-blocking glasses such as the inexpensive Uvex SCT Orange model. I’ve been using these for about a year and they work well I notice myself feeling more tired almost immediately after putting them on. Controlled trials have confirmed that blue-blocking glasses completely restore melatonin secretion (3, 4), presumably eliminating the effects of artificial light on the SCN clock.
Another great tool is F.lux, a free computer program that automatically changes your monitor’s color spectrum based on the time of day. I’ve been using this for about two years, and previously felt that it wasn’t able to remove enough blue light to be very useful. I recently realized that they upgraded it in a way that makes it much better. If you pull up the program, click on the three horizontal lines to the right of the settings menu, and scroll over the “lighting at night” menu, you will see seven options for color temperature ranging from “sunlight” to “ember”. I’ve found that when I dim my monitor, the ember setting is equivalent to wearing blue-blocking shades while I use my computer. In fact, I’m feeling sleepy right now as I write this.
In the Ideal Weight Program, we focus on improving sleep quantity and quality in part by using skillful light exposure to naturally guide the SCN clock to a healthy day-night cycle. F.lux is a useful tool that we highly recommend.
Written by Stephan J. Guyenet, Ph.D., co-developer of the Ideal Weight Program
Recently, I wrote an article entitled Reducing stress in the hypothalamus – is this the best way to decrease body fat? In that article, I discussed how inflammation of the brain’s body-fat regulator – or ‘fat thermostat’ – is of critical importance for weight management. In this article, I discuss how certain dietary patterns affect inflammation in the fat thermostat, as well as short-and-longer term outcomes of different diet types.
It was traditionally thought that total brain blood flow was not changed during physical activity. Research in the last 10 years, however, changed this perspective. We now understand that the increased neuronal and metabolic activity of the brain during exercise drive increases in blood flow to it. We have also learned that exercise that is too intense will reduce blood flow and oxygen delivery causing fatigue. So, what is the ideal intensity to stimulate blood flow to the brain, and perhaps, augment your mental abilities in the moment?
When we think of foods that improve athletic performance, chocolate is maybe not one of the first options that comes to mind.
We’ve known for a while that certain molecules found in chocolate, known as flavonols, are associated with health benefits to the heart and the brain. Epicatechin, in particular, has exhibited widespread effects throughout the body.
But some emerging evidence suggests that chocolate may also aid in exercise performance – weird as it may sound.
Here’s what the research says so far, and how it seems to work.
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.
We do not enter into the world with infinite knowledge of ourselves and our surroundings. We don’t have knowledge or skill to survive, to dance, or to do martial arts with grace and efficiency. We don’t know enough about ourselves or know how to interact best with different types of people we encounter. We don’t know how to accelerate our ability to get better at something. We are born, however, with the capacity to learn and to remember, and by virtue of this skill, we have an incredible potential to do great things.
Professor Marcos FrankToday, important stuff happened to you. Tonight, when you sleep, your brain will extend the process of turning that stimulation – the sites, sounds, thoughts, emotions, facts, etc. – into memories that you can access at a moments notice in the future. It’s amazing when you think about it: experiences, facts, skills, and even thought patterns become a part of who we are. How much do you know now that you didn’t know 1o to 15 years ago, or even last week, last month, or yesterday? The process of accumulating information, and accessing when needed, is so routine it’s easy to forget that something is going to make it possible. As it turns out, sleep plays a vital role in the formation of certain types of memories. In this interview, I speak with someone who has made, and continues to make, significant contributions to help the world better understand how all this magic works. My guest is Marcos Frank, Ph.D., who is the Interim Chair of the Department of Biomedical Sciences in the Elson S. Floyd College of Medicine at Washington State University. I hope you enjoy this discussion as much as I did.