“A first-of-its-kind experiment tracking fruit fly behavior in a natural setting challenges 40 years of assumptions about circadian clocks.

The research, published today (April 4) in Nature, suggests that much of scientists’ current understanding about Drosophila circadian behavioral rhythms may actually be wrong. It also emphasizes the importance of studying organisms in natural environments….”

the metal halide bulb, which gives off a white light and is used for stadium lighting, among other uses, suppresses melatonin at a rate more than 3 times greater than the HPS bulb, while the light-emitting diode (LED) bulb, which also gives off a white light, suppresses melatonin at a rate more than 5 times higher than the HPS bulb.

“The current migration from the now widely used sodium lamps to white lamps will increase melatonin suppression in humans and animals,” the researchers say.

The researchers make some concrete suggestions that could alter the situation without throwing our world into total darkness, but first and foremost, they assert that it is necessary to understand that artificial light creates “light pollution” that ought to be addressed in the realms of regulation and legislation.

Their first suggestion of course, is to limit the use of “white” light to those instances where it is absolutely necessary. Another suggestion is to adjust lampposts so that their light is not directed beyond the horizon, which would significantly reduce light pollution. They also advise against “over-lighting,” using only the amount of light needed for a task, and, of course, to simply turn off lighting when not in use — “Just like we all turn off the light when we leave the room. This is the first and primary way to save energy,” the researchers say.

“Most Italian regions have legislations to lower the impact of light pollution, but they still lack a regulation on the spectrum emitted by lamps. Unless legislation is updated soon, with the current trend toward sources as white LEDs, which emit a huge amount of blue light, we will enter a period of elevated negative effects of light at night on human health and environment. Lamp manufacturers cannot claim that they don’t know about the consequences of artificial light at night,” says Dr. Fabio Falchi of ISTIL.
….

http://ehp03.niehs.nih.gov/article/info%3Adoi%2F10.1289%2Fehp.118-a22

brief excerpt:

… blue’s benefit, and its detriment, are both a matter of timing. In one experiment, Kunz showed that exposing healthy subjects to 30 minutes of 500 lux polychromatic blue light an hour before bedtime, in their natural home environment, delayed the onset of rapid eye movement sleep by 30 minutes. The implications of that finding have yet to be determined, says Kunz. But the melanopsin receptors are particularly sensitive during the evening and nighttime hours, so “I’m pretty sure that at least many of the sleep disorders we are facing epidemically are related to evening or nighttime light,” he says. According to the National Center on Sleep Disorders Research, sleep-related problems affect 50–70 million U.S. men and women of all ages.

Kunz and others also suspect that outdoor artificial night lighting aggravates circadian disruption, although he says there is a dearth of human data on the subject. [For more information about artificial light at night, see “Missing the Dark: Health Effects of Light Pollution,” EHP 117:A20–A27 (2009).]

Why blue? Blue’s power to reset circadian rhythms is not intrinsic to the color. A photoreceptor for any color could have evolved to signal daylight to the suprachiasmatic nucleus. But the blues more easily penetrate the surface of the oceans—where life (and photoreceptors) likely first evolved—than do other visible wavelengths. The color balance of the sky may have helped to preserve blue’s clock-setting role throughout evolutionary history….

“… our world is increasingly illuminated in blue. By one estimate, 1.6 billion new computers, televisions and cellphones were sold last year alone, and incandescent lights are being replaced by more energy-efficient, and often bluer, bulbs.

In January in the journal PLoS One, the University of Basel team also compared the effects of incandescent bulbs to fluorescents modified to emit more blue light. Men exposed to the fluorescent lights produced 40 percent less melatonin than when they were exposed to incandescent bulbs, and they reported feeling more awake an hour after the lights went off.

In addition, the quantity of light necessary to affect melatonin may be much smaller than once thought. In research published in March in The Journal of Clinical Endocrinology and Metabolism, a team at the Harvard Medical School reported that ordinary indoor lighting before bedtime suppressed melatonin in the brain, even delaying production of the hormone for 90 minutes after the lights were off, compared with people exposed to only dim light….”

http://www.nytimes.com/2012/02/21/health/aging-of-eyes-is-blamed-in-circadian-rhythm-disturbances.html

Aging of Eyes Is Blamed for Range of Health Woes
By LAURIE TARKAN
Published: February 20, 2012
THE HYPOTHESIS: The aging eye filters out blue light, affecting circadian rhythm and health in older adults.

“this study represents a preliminary attempt to provide insight into the relationship between daytime exposure to light and night-time sleep in young, healthy infants. No intervention or manipulation of light or behavioural routine was attempted …. a relationship was found between light exposure and babies who showed an early propensity for sleep at night and activity during the day. … High levels of light exposure may not be necessary as Waterhouse et al. (1998) reported that even domestic levels of light can influence the human circadian system, and that it is the timing, rather than intensity of light which is of crucial importance. …”

“My Tot Clock

My Tot Clock is the first all-in-one sleep clock, alarm clock, nightlight, timeout timer, and activity timer for tiny tots who can’t yet tell time. The magic of My Tot Clock is that it changes color to teach little ones when it’s time to sleep (blue light) and when it’s okay to wake (yellow light)….”

Got that exactly backwards. I wonder what wavelength of blue they’re using.

hat tip to: http://www.squidoo.com/kids-sleep-clock

(Me, I’ll stay with the $25 dawn simulator I recommended much earlier in the thread)

“Wake Up Light
By Rocky Sand Studio
Mac App Store

Wake Up Light is a special alarm clock for your Mac. It wakes you up with gradually brightening light to help you feel more energized all day. The beautiful sunrise effect is a natural cue for your body to increase the level of cortisone, which is also referred to as the energy hormone.

Wakeup Light simulates sunrise at the speed of your choice, so you can adjust it to suit your personal preference. The light will be at it’s brightest at the alam time you set and a natural alarm sound will start to play at a selected volume….”

“… Tech visionaries have promised us a bright new world where cool and efficient white LEDs, based on blue ones, will replace the wasteful little heaters known as incandescent lightbulbs…. ”
http://spectrum.ieee.org/semiconductors/optoelectronics/the-leds-dark-secret

(No, to the IEEE, the ‘dark secret’ isn’t that it screws up biological day/night cycles, it’s that it’s not yet cheap enough to use everywhere at high brightness levels.)

mechanisms start to connect how light affects other processes

http://www.sepeap.org/imagenes/secciones/Image/_USER_/5_circadian_mechanisms_in_the_regulation_of_melatonin_synthesis_disruption_with_light_a_%20night_and_the_pathophysiolog.pdf

March 2011 Gooley et al. 96 (3): E463
JCEM Online: Hot Topics in Translational Endocrinology

Exposure to Room Light before Bedtime Suppresses Melatonin Onset and Shortens Melatonin Duration in Humans
http://jcem.endojournals.org/content/96/3/E463.short
Design:In a retrospective analysis, we compared daily melatonin profiles in individuals living in room light (<200 lux) vs. dim light (<3 lux).

Short answer: it depends (quite a bit on how your employer manages lighting — if they’re using dimmer lights in the evening for example. Did you look at that link in the post right before yours?
http://psychcentral.com/blog/archives/2007/03/12/light-and-dark/#comment-719892

(A reference librarian can find the study for you — it’s paywalled online. And there’s a whole lot out there about shift work generally)

But you might try Google’s search — their “natural language search” tool keeps improving. Here’s your question as a search in ordinary Google:
http://www.google.com/search?q=how+does+working+night+shift+affect+ADHD+and+depression

Same, but limited to PsychCentral cite (a very handy tool) the search turns up several topics that are lively and might have an answer for you:
http://www.google.com/search?q=site%3Apsychcentral.com+how+does+working+night+shift+affect+ADHD+and+depression%3F
And for (mostly) science results:
http://scholar.google.com/scholar?q=how+does+working+night+shift+affect+ADHD+and+depression%3F

http://www.nlm.nih.gov/medlineplus/news/fullstory_117012.html

By Mary Elizabeth Dallas
Thursday, September 29, 2011
HealthDay news image

THURSDAY, Sept. 29 (HealthDay News) — Working rotating shifts is not as potentially unhealthy as it used to be, according to new Canadian research that suggests modern shift patterns may not carry the same risks for cancer as older, more extreme shift schedules.
… the study’s lead author, Anne Grundy, a doctoral student in the Queen’s University department of community health and epidemiology in Ontario, said in a university news release. “Our study indicates that the now common rotating shift pattern of day-day-night-night may not disrupt circadian rhythm or melatonin production significantly.”

Melatonin, a hormone shown to have anti-carcinogenic qualities, is tied to the light-dark cycle, and melatonin levels typically peak between midnight and 4 a.m. As a result, shift workers who are exposed to light throughout the night may have an increased risk of diseases such as cancer. The study found, however, that recent changes in how shifts are scheduled may help reduce the health risks for these workers. [...]

LSG quit selling them after a while.

Well, if they have a new product that blocks the band that suppresses melatonin, I’ll be delighted. I hope it’s coming soon.

Of course at other times of day you’ll want lamps that _provide_ the critical band so keep you awake — they’re available without the extra glare and risk of the old super-bright-white lights — Sunnex Biotech, http://www.sunnexbiotech.com/ — which I recommended a while back in the thread. I’ve been using theirs (or the Rosco theatrical gels that produce the same result) for the past few years for the wake-me-up-and-set-my-clock hours.

Circadian Phase Delay Induced by Phototherapeutic Devices
Aviation, Space, and Environmental Medicine, Volume 78, Number 7, July 2007 , pp. 645-652(8)

http://www.ingentaconnect.com/content/asma/asem/2007/00000078/00000007/art00001;jsessionid=1lquvkvh40oo0.alexandra