Devices that gradually illuminate a sleeper’s environment prior to wake can be easier for patients to use than traditional bright light therapy. Though not as powerful, the simulators have shown promise for various sleep/wake disorders.
In 1980, researchers found that exposing a person to high-intensity light caused an immediate but temporary cessation in melatonin production.1 This finding led to the use of bright light to shift a person’s melatonin production, and consequently the sleep/wake cycles, to a more preferred time to treat circadian rhythm disorders or to improve the sleep of people who work the night shift or shift work or to lessen the effects of jet lag.2-4 Bright light therapy is also used to treat seasonal affective disorder (SAD) and other types of depression.5
A recent outgrowth of light therapy research is dawn simulation research. Dawn simulators expose sleepers to a slowly increasing intensity of light for 30 minutes or more before awakening. Some dawn simulators also double as sunset simulators (that is, light begins to decrease gradually about 30 minutes before a set bedtime). Scientific interest in determining whether a more naturalistic exposure to light improves sleep and mood has shown some interesting findings.
Dawn Simulation Research
In 1989, Terman and colleagues were the first scientists to describe the effects of dawn simulation in humans.6 In their study, participants with seasonal affective disorder were exposed to either simulated sunrise or both simulated sunset and sunrise for several days. After treatment, depressive symptoms either resolved or were greatly reduced in most participants. With treatment, the participants were able to fall asleep within 30 minutes of simulated sunset. The circadian rise and fall of melatonin production occurred earlier (ie, advanced phase shift) with sunrise simulation or with sunset plus sunrise simulation.
Many researchers subsequently examined the impact of dawn simulation on different aspects of SAD. For example, some research indicates that dawn simulation improves sleep inertia,7,8 cognition,8 performance,8 and mood9 in people with SAD. In recent years, researchers have broadened their focus on the impact of dawn simulation on other disorders such as an advanced circadian rhythm in people with dementia and bipolar disease, and the results have been promising. In a Swiss study, patients with dementia were exposed to simulated sunset and sunrise (the simulator began decreasing the light intensity approximately 45 minutes before bedtime and increasing light intensity approximately 30 minutes before awakening); this treatment decreased sleep latency and increased sleep duration.10 In a study comparing the effects of dawn simulation and bright light on symptoms of bipolar disorder and SAD, researchers found that the response to dawn simulation was similar to that of bright light therapy, and therefore dawn simulation could be an alternative to bright light therapy.11
Because dawn simulation causes an advanced phase shift,12 the treatment may be beneficial for people with circadian rhythm disorders (such as delayed sleep phase syndrome or non-24-hour sleep-wake disorder) or who may experience jet lag. Similarly, pediatric populations such as teenagers who experience sleep phase delay may benefit from dawn simulation. Neal Owens, president of The Sunbox Company, says, “Parents with kids find that dawn simulation devices are extremely helpful. Most parents say it was the best investment they have made to get their kids up and going in the morning.” These populations have not yet been examined in depth in peer-reviewed journals.
Dawn simulation, by allowing a slower awakening from sleep, may protect against early morning adverse cardiovascular events (for example, stroke, angina), which scientists suspect may be associated with sudden sympathetic activation.13 More research is needed to examine to what extent dawn simulation may reduce the risk of early morning cardiovascular events.
Similarities, Differences to Bright Light Therapy
In a recent study, a Russian research team headed by Konstantin Danilenko found that bright light treatment may be more beneficial in relieving symptoms in people with severe SAD compared to simulated dawn therapy.9 In their study, participants underwent bright light therapy and weeks later were crossed over to undergo simulated dawn therapy. After undergoing both treatments, some patients expressed a preference for bright light therapy and others for dawn simulation. In the former group, bright light therapy had provided greater relief of symptoms, compared to dawn simulation treatment. In the latter group, bright light therapy and dawn simulation treatment had the same effect on relieving symptoms. Hence, the severity of symptoms may need to be considered with regard to the efficacy of dawn simulation for a person with SAD.
Bright light therapy requires active effort from a patient to be effective, whereas dawn simulation does not. “The eyes appear to respond to light transmitted through a sleeper’s closed eyelids,” Owens says. “The light promotes beneficial changes in mood-related brain chemistry. With light therapy, the eyes need to be opened for the therapy to do its job.”
In bright light therapy, a special unit—the light box—contains bulbs that emit light at an intensity of 2,500 to 10,000 lux. A person typically sits before the light box for 15 to 30 minutes after awakening (to induce a phase shift advance) or soon before going to bed (to induce a phase shift delay). To maintain the antidepressive effects or a desired shift in the circadian rhythm, the therapy has to be used at the same time daily. In dawn simulation, the dawn simulator typically contains a timer, a rheostat (the component that allows the gradual increase in light intensity), and a bulb that emits light at an intensity of 100 to 300 lux. Approximately 30 minutes before a desired wake time, the bulb comes on at its lowest intensity, slowly increases in intensity, and reaches its highest intensity by the person’s desired wake-up time. The person ideally awakens spontaneously.
In recent years, dawn simulator manufacturers have improved their devices to make them increasingly user-friendly. Some plug into a person’s existing bedside lamp and use its bulb to provide the light. Steve Chang, owner and founder of The Up Light Corp, says the company’s dawn simulators provide 16 million color options, allowing users to customize their sunrise experience. Chang explains, “Customers can experience longer warm color temperatures for a gentler sunrise or a more aggressive simulation where they’ll get longer cool/blue 6,000k+ spectrum exposure, depending on their sensitivity and preference.” The UpLight can also double as a sunset simulator in which it will gradually dim the light during a period set by the user and then turn the light off. “We felt these features were critical as the light you experience at night has as much of an impact on your sleep/wake cycle as the light you experience in the mornings,” Chang says.
Dawn simulation has some advantages over bright light therapy. Because dawn simulation requires less active effort, a user may be more compliant with using it consistently. Dawn simulation is subjectively experienced as “more natural,” which may also contribute to more compliance. For some people, dawn simulation may be an alternative if the higher-intensity light used in bright light therapy has adverse effects such as eye strain, glare, or agitation.
However, dawn simulation therapy has some drawbacks. “Previously, with dawn simulators, typical patient complaints were price [units cost on average $100 or more]; they were clunky and didn’t fit their decor, or they couldn’t customize it,” says Chang. “But those are things that simulators like The Up Light have addressed, and the industry has made significant progress.” Chang also advises that patients’ expectations should be set at realistic levels, saying some patients expect the devices to work like alarm clocks—waking them up instantly the first morning. “Dawn simulators work more on a biochemical level so it’s not a one day/next morning quick fix,” he says.
Kirk Renaud, BioBrite Inc CEO, says, “Dawn simulators are not as powerful as bright light therapy boxes and visors for treating serious cases of SAD and circadian-related sleep disorders. However, they can be an excellent complementary therapy.” Many people who use bright light therapy products find it especially challenging to get out of bed in time to use a light box, but a dawn simulator can give them the jump start they need to get the day going, and then they are better able to comply with their bright light regimen, Renaud says. The same can be said for people who use bright light to phase shift sleep patterns. They can use a dawn simulator to reinforce the sleep program they are following.
The more naturalistic awakening provided by dawn simulators appears to improve mood and sleep. However, more research is needed. Future research may more definitively determine who can most benefit from dawn simulation and for whom dawn simulation is contraindicated, and determine its effect in other populations such as people with impaired vision and night shift workers.
Regina Patrick, RPSGT, RST, is a freelance medical editor/writer for the Regina Patrick Writing Service. She covers numerous sleep medicine topics for Sleep Review.
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