Saturday, April 12, 2014

Wake-Up Light as Natural Ergogenic: Dawn Simulation Increases Early Morning Physical & Cognitive Performance

What could be better than starting your day with the first rays of the sun? Doing this with a person you love, I suppose.
If you have listened to Super Human Radio earlier this week (download episode), you will have heard that Carl "caught" me off guard calling me without prior notice during the live show. We ended up talking about the use of melatonin and my beloved "daylight lamp" (light therapy lamp), which kept my energy levels up even at the darkest winter mornings over the past couple of months.

If you listened to the show, you may also remember that Carl mentioned that it would be great to have a light-based alarm clock - something like a light therapy lamp that increases its intensity gradually at a given time and will thus wake you up from a deep slumber.
You can learn more about sleep and the circadian rhythm at the SuppVersity

Sunlight, Bluelight, Backlight and Your Clock

Sunlight a La Carte: "Hack" Your Rhythm
Breaking the Fast to Synchronize the Clock

Fasting (Re-)Sets the Peripheral Clock

Vitamin A & Caffeine Set the Clock

Pre-Workout Supps Could Ruin Your Sleep
Well, I already mentioned during the show that a corresponding device is already available, but pretty useless for someone who usually uses blindfolds to get a good night's sleep. For the rest of you, who are sleeping in a pitch black room without covering their eyes with a blindfold, on the other hand, Carl's suggestion could be a viable means to "improve both cognitive and physical performance after waking." (Thompson. 2014).

This is at least what a recent study from the University College London would suggest. For the corresponding experiment, the researchers from the Department of Epidemiology and Public Health recruited 8 young adults (four males; four females) with a mean age of 24 ± 9 years who had not been involved in nocturnal shift work or undertaken transmeridian travel during the past 30 days (that's important to ensure that their circadian rhythm was not messed up in the first place).
Dawn Simulation? How did that work? Two dawn simulation devices (Lumie Bodyclock Active 250) were placed at either side of the participants’ bed at a distance of 30 cm to ensure they were exposed to the light. thirty minutes prior to waking, dawn simulation was initiated, starting at 0.001 lux and rising to 300 lux following a sigmoidal illumination ramp. Accuracy was confirmed by measurement of illuminance with a digital photometer.
The trials themselves were ordered in a counterbalanced fashion and were separated by 5–9 days. In the two days leading up to the tests, the participants were asked to sleep the exact times in their own homes that they would in the laboratory. to monitor compliance wrist accelerometers were issued.
Did you know that previous studies support the use of dawn simulations to tread seasonal effective disorder, where it was on top of that associated with lower remission rates than regular light therapy (Avery. 1993 & 2001). In addition, dawn simulations have been shown to have beneficial effects on the necessary and natural and healthy (Clow. 2010) early morning increase in cortisol (Thorn. 2004)?
"The experimental trials were identical with the exception of the 30 min prior to waking. During this time par ticipants either slept normally in complete darkness, the control condition (c), or were exposed to dawn simulation (DS).

Each night’s sleep ended with an audible alarm. At the same moment, a researcher entered the room to ensure that the participant was awake. Participants were then allowed to attend the bathroom if required.

After waking, a 75 min testing protocol commenced which consisted of: three bouts of cognitive assessment, one physical performance test and monitoring of physiological and subjective variables." (Thompson. 2014)
In view of the fact that I already gave away the results, it's probably not really surprising that the data in Figure 1 confirms that being waken up by artificial sunlight had significant beneficial effects on the cognitive and physical performance of the subjects.
Figure 1: Changes in number of total additions and reaction time in cognitive tests (Thompson. 2014)
What did not differ, though, were the sleep efficiency, sleep latency, and the total sleep time. In a similar vein, the differences in perceived sleepiness and body temperature were visible, but not statistically significant.
The Philips Wake Up Light, I mentioned on the air has a similar 300lux daylight lamp as the device used in the study at hand.
Bottom line: Overall my good friend Carl Lenore was thus (once again) right. Emulating the Sun's "natural" wake-up call will get your body and mind going in the morning. The fact that this worked with only 300 lux and eventually being woken up by the usual nasty alarm clock is telling me that it may be worth checking what happens if you ditch the alarm clock altogether and increase the light intensity from 0 to 10,000 lux so that the light and not the alarm clock wakes you up.

Whether this or the addition of a "post-wake-up" session in front of a light therapy lamp, as the one I use, provides additional benefits, would yet have to be verified in a controlled trial.
  • Avery, David H., et al. "Dawn simulation treatment of winter depression: a controlled study." American Journal of Psychiatry 150 (1993): 113-113.
  • Avery, David H., et al. "Dawn simulation and bright light in the treatment of SAD: a controlled study." Biological psychiatry 50.3 (2001): 205-216.
  • Clow, Angela, et al. "The cortisol awakening response: more than a measure of HPA axis function." Neuroscience & Biobehavioral Reviews 35.1 (2010): 97-103.
  • Thompson, Andrew, et al. "Effects of dawn simulation on markers of sleep inertia and post-waking performance in humans." European journal of applied physiology (2014): 1-8.
  • Thorn, Lisa, et al. "The effect of dawn simulation on the cortisol response to awakening in healthy participants." Psychoneuroendocrinology 29.7 (2004): 925-930.