Is being a light sleeper a medical condition?

Is there a resource--using lumens or whatever--to evaluate required light levels for various plants/condition?

• Perhaps a handy chart or species-to-lumen-range database? Obviously, terms like light shade, deep shade, dappled sun, and even full sun can be all too ambiguous. For example, I have a large area of a residential landscape where the limited degree of shade is from very tall trees whose leaf-cover is not dense and there are also many moderately reflective surfaces providing additional ambient light. Therefore, based upon the performance of various plants which normally require "full sun", I am prone to think that these particular "bright shade" conditions are only slightly less luminous that what is considered "full sun" in this climate. Or perhaps not. After all, human perceptions of light conditions are extremely subjective and are further complicated by the portions of the spectrum provided by the light source, the relative angle/position of the light source, and the cooperation of the iris. So, with the help of my cheap photometer, I would like to evaluate this area of the landscape to see if it is close enough to full sun to allow me to introduce some sun-loving plants -- especially those whose degree of blooming are likely to be negatively impacted if the area is not bright enough. Indeed, that is my primary goal: figuring out if the "light shade" of the area is perhaps a help in reducing some of the possible leaf-burning of the mid-day sun and yet providing enough lumens to support profuse blooming of butterfly bushes (Buddleia davidii), passion flower (Passiflora coccinea), morning glories, and perhaps even some tomato plants or melons. Perhaps someone has found a convenient summary chart online or some reference resource which provides lumen ranges. (Yes, I understand the complications of various units of measure such as lux and candela. So I can adapt the reference source if necessary. And I also realize that a "full sun" in Anchorage is very different from the same expression in Miami. But that is all the more reason to resort to more objective measures.)

• Answer:

  Hey IGAT Metrics, The following is an excerpt from the first web site - although somewhat technical, so is your question. Plants after all need light in greater ranges than humans. That first web site includes a 7 step process for determining your requirements in an area - worth it to you to check out. --------------------------------------… 1 Since plants use energy between 400 and 700 nanometers and light in this region is called Photosynthetically Active Radiation or PAR, we could measure the total amount of energy emitted per second in this region and call it PAR watts. This is an objective measure in contrast to lumens which is a subjective measure since it is based on the response of the subjects (humans). PAR watts directly indicates how much light energy is available for plants to use in photosynthesis. The output of a 400 watt incandescent bulb is about 25 watts of light, a 400 watt metal halide bulb emits about 140 watts of light. If PAR is considered to correspond more or less to the visible region, then a 400 watt metal halide lamp provides about 140 watts of PAR. A 400 watt HPS lamps has less PAR, typically 120 to 128 watts, but because the light is yellow it is rated at higher lumens (for the human eye). "Illumination" for plants is measured in PAR watts per square meter. There is no specific name for this unit but it is referred to as "irradiance" and written, for example, as 25 watts/square meter or 25 w/m2. What is a "good" level of lighting for plant growth? This level depends on a number of factors, including plant type, stage of growing cycle, response to increased light levels, among others. Recommendations offered in technical brochures or articles should be treated as rough guidelines. Within a broad range, plants grow faster with more light; therefore the cost of electrical power versus the benefit of faster or higher growth plays a role. Since lamp to lamp variations, light depreciation over life, fixture degradation from dirt and line voltage fluctuations all contribute to variability, calculating to three decimal places is unnecessary! As an example, if a specific technical brochure recommends a PPF PAR irradiance of 400 µmol.m-2.s-1 for your plants, the table below shows that you need approximately 85 PAR watts/square meter. The conversion factors between PPF PAR, PAR Watts and lux depend on the light source. For example, a 400 watt HPS lamp has more lumens than a 400 watt metal halide lamp but fewer PAR Watts. Depending on the color temperature of the metal halide lamp, there can be small variations in the conversion factors. --------------------------------------… 2 How much Light do I need? A: 20-40 watts per sq. ft. is a general guideline. The more efficient the Light source, the less watts per sq. ft. needed. For example using 1-1000 watt metal halide light, in a 50 sq. ft. area would give you 20 watts per sq. ft. and a total of 120,000 lumens. Compare this to 3-400 watts metal halide lamps in the same space which will give you 24 watts per sq. ft. and a total of 120,000 lumens. You will get more light from a single 1000 watt light while using less wattage per sq. ft. in addition to savings on timers, and outlets. As a rule, 20 watts per sq. ft. using 1000 watt metal halides is the absolute minimum required. Since a given amount of light can only do so much, the same production can be obtained in a smaller space with less plants because the light is concentrated, and the plants can work more efficiently. Using more light also helps additional CO2 up take.