Research in circadian rhythms in recent years seems to indicate that they are very important for overall health.

Just as it is important with darkness before and during sleep, it also appears to be very important with appropriate light when waking up in the morning. Some studies using simulated dawn have shown positive results and lend support to the notion that the correct amount of light is indeed important when waking up.

One such study Effects of dawn simulation on markers of sleep inertia and post-waking performance in humans was published last year and examined the effects of different light in the morning.

The design of the study is very simple. Eight young adults slept under strict surveillance in a sleeping lab on three different occasions. On the first occasion, they were to get acquainted with the new surroundings, tests, etc. But for the two subsequent sessions, the participants were randomly assigned to either wake up to a regular alarm clock or a kind of wake-up light or simulated dawn (SD). The participants were then subjected to several different tests and measurements – both cognitive and physical.

Wake-up Light Makes you Feel more Alert in the Morning

The results indicate that SD made the participants feel more alert in the morning. The participants who were woken up by light instead of sound performed better on both physical and cognitive tests.

The figure to the right shows the participants’ self-perceived alertness from until the moment they woke up until 75 minutes later.

Feeling energetic is certainly nice, but the question is whether this actually transferred to any kind of actual increase in performance. The other figure to the right shows the results from a reaction test that the participants were subjected to 30 and 75 minutes after they woke up. The reaction test was done on a computer and measured the fastest reaction times. The participants’ response was improved when they awoke with SD.

The researchers also measured physical performance and also here there was a notable improvement for the group who woke up to SD. The method used to measure this was a time trail on a bike. Simply, the faster you were able to finish a 4-kilometer stretch, the better. Those participants who woke up with SD performed better on the fitness test. Simulated dawn improved performance with an average of 4 percent for SD participants when the fitness test was performed 35 minutes after waking up.

Same Effects on a Longer Time Frame?

This study thus shows positive effects when waking up with light instead of sound. It thereby confirms results seen in a couple of previous studies. People do feel more alert and perform better immediately after awakening if they wake up to a simulated dawn compared to a regular alarm clock.

However, this is the acute effects. The perceived alertness between the two groups was equal 75 minutes after they awoke. Keeping in mind that the participants in the study were subjected to a couple of cognitive tests and a physical fitness test during this time, however, this probably contributed to bringing the two groups closer to each other faster.

Regardless, it seems as if “sleep inertia” is improved. As we humans are a little sluggish starting up in the morning, it takes about two hours until we are able to perform at an optimal level.

Another recent epidemiological study showed that people who are exposed to daylight early in the day tend to weigh less than people who are not exposed to any bright light in the morning. Perhaps this is an indication of waking up to sunlight, does improve health.

There are quite a lot of lamps available on the market designed to simulate dawn. And the simple answer if its worth testing is probably, why not? If you like most people hate your alarm clock, perhaps you are just curious, most lamps aren’t very expensive.

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Thompson A1, Jones H, Gregson W, Atkinson G. Effects of dawn simulation on markers of sleep inertia and post-waking performance in humans.
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