Post: #1

I have mentioned bright light therapy in a number of previous posts on the forum, as well as recommended it to some posters in PMs. But I thought it would be useful to post a reference thread that explains what bright light therapy is, summarizes its benefits, and contains detailed instructions for maximizing these benefits.

I will preface the below by saying that, in my opinion, bright light therapy is the single most effective tool for getting on and maintaining a regular sleeping schedule and enjoying high quality sleep, night in night out. In addition, it is one of the most effective ways to reduce depression and anxiety for those that suffer from them -- either seasonally or otherwise. These are not just opinions -- they have been confirmed by extensive research, and I have personally observed the benefits of bright light therapy in a number of people I know. Best of all, it is extremely safe and has no negative side effects whatsoever when used correctly.

Now, I am going to describe what bright light therapy is, what its benefits are, and how it should be used to maximize these benefits.

1. What is bright light therapy?

It's very simple. You sit next to a light box containing fluorescent bulbs that radiate bright light of the same frequencies as natural sunlight in the visible spectrum (but filtering out the ultraviolet frequencies). This way, you effectively absorb a very large intensity (10,000 lux) of natural sunlight in a relatively brief amount of time (20-30 minutes). It looks like this:



2. What does it do and how does it work?

The 24 hour cycle of daylight and darkness is the most basic fact about our natural environment and dictates the circadian rhythms that modulate sleep and wakefulness. Therefore it is unsurprising that absorption of sunlight in the visible spectrum directly affects the biological pathways that are most relevant to the sleeping/waking cycle. That cycle, in turn, is intimately related to mood and overall sense of well-being. States of depression and anxiety, almost without exception, involve and indeed require dysregulation of the sleeping-waking cycle.

The correct use of bright light therapy cues the brain in the morning to start the circadian cycle for the day at the right time. As a result, the different stages of wakefulness and sleep become properly regularized. You go through the day feeling wakeful and having good levels of energy, you start getting "sleep tired" and fall asleep reliably at around the same time each night, and you then wake up at the same time the following morning following a night of correctly structured and restorative sleep. This is the ideal way that our sleep/waking cycle should proceed for a healthy body and a healthy mind -- at regular and consistent intervals, repeated like clockwork. The cuing through bright light therapy achieves this.

In addition (and as I said, these things cannot really be separated from each other because of their intimate biological connections) bright light therapy, correctly administered, is extremely effective at reducing symptoms of depression and anxiety -- including, but not limited to, the so called "winter blues" or SAD (Seasonal Affective Disorder).

Best of all, bright light therapy when used correctly has no negative side effects -- none.

In my opinion (and I'm not the only one who thinks this and has said it) if bright light therapy was a drug it would be the best-selling drug in the world. It is extremely effective, reliable, and has zero side effects. The only reason it is not more well-known is because it cannot be marketed by a pharma company.

3. What is the right way to use bright light therapy?

The key is consistency. You want to do it every morning, relatively soon after you wake up, for the same amount of time (20-30 minutes) at the same intensity (10,000 lux).

Depending on the exact box you're using, you sit at between 15'' - 23'' from the box to achieve the 10,000 lux intensity. You don't look directly at the bulb, but across it. Make it part of your morning ritual -- you can have your breakfast, read the paper, and so on. Again, it looks like this:



To repeat the keys are:

-- use same time every morning soon after you wake up
-- 10,000 lux at the correct distance (typically 15'' - 23'', depends on the exact product)
-- 20-30 minutes, looking across the light box as shown in the picture

4. Links, FAQ, Etc

There is a great deal of research that supports the statements and suggestions I made above. Here are some selected links:

Nice Q&A from Columbia University
Mayo Clinic write-up
Wiki
One of the original studies
Harvard Med School write-up

In addition, I can speak from personal observation. While I am blessed to be a naturally good sleeper and have not needed bright light therapy myself, I sent light boxes to people I know closely -- including my mother and my aunt -- who were having serious trouble sleeping, as well as problems with stress and anxiety. The results were great in every case I have personally observed so far: these people started sleeping much better within days, and have experienced very substantial relief of their anxiety and depressive symptoms.

Two other quick points to make:

-- Light boxes radiate visible spectrum light only. They filter out the ultraviolet frequencies (as I already mentioned above). That means that you do not get UV radiation from a light box -- so you can't get tanned from it, or be exposed to dangerous (or any) amounts of UV. This also means that it will not stimulate production of vitamin D (that is done by the UV frequencies). A light box is not a replacement for natural sunlight -- you still need that UV. Rather, it uses a heightened intensity of visible spectrum light at the right time to correctly cue your circadian rhythms.

-- Although bright light therapy is not only for fall/winter, there is a reason I'm posting this thread at the end of August. This is a time of year when the duration of natural daylight is rapidly decreasing (if you are in the Northern hemisphere), and many people begin struggling with their sleep, mood and energy levels. For many people, this is the most natural time of the year to start thinking about bright light therapy.

5. Product Suggestions

I like light boxes made by the SunBox company (they're the original manufacturer that started making them in the US). They're reliable and of great quality. In particular, I like this one:

Sunlight Jr.

There are also other companies that make these, but in my opinion quality makes a real difference, so I would not go for one of the cheapest models. These things last forever, so it's not like you're going to be replacing them. It's a one time investment.

*************************************

I hope guys who have trouble establishing a good regular sleeping schedule, or who feel that they are suffering from low energy levels, depression-like symptoms, or anxiety, consider this very under-appreciated, and exceptionally safe, therapeutic modality.

Post: #2

Can you give a recommendation regarding sunlight boxes vs. blue-light boxes?

Post: #3

(09-01-2014 02:42 PM)void Wrote:  Can you give a recommendation regarding sunlight boxes vs. blue-light boxes?

Yes. I strongly recommend using full spectrum light boxes (like the one I linked to in the OP) rather than blue-light or red-light boxes.

All the best research showing the effectiveness of bright light therapy has been done with full spectrum boxes, and they have the best and longest track record. And since our bodies and brains have evolved in the presence of full spectrum natural sunlight, there are probably very good reasons why full spectrum light boxes are optimal.

Post: #4

Good thread. I used a 'Philips Go-Lite' blue light a couple of years ago and my I noticed an instant change in my mood and the time it took me to fall asleep. The effect it had on my Seasonal Affective Disorder was so good that I consider it one of the best investments I've made. Well worth the $100 or so.

If I'm in the Northern Hemisphere during the winter I consider the blue-light a must. I might now look into light boxes.

OP - would you bother if you were living near the equator?

Post: #5

(09-01-2014 03:27 PM)el conquistador Wrote:  Good thread. I used a 'Philips Go-Lite' blue light a couple of years ago and my I noticed an instant change in my mood and the time it took me to fall asleep. The effect it had on my Seasonal Affective Disorder was so good that I consider it one of the best investments I've made. Well worth the $100 or so.

Yep, the effects are startling and kick in very rapidly. Indeed, it's one of the best investments anyone could ever make. It's really too bad that this is not better known -- again, pharma companies hate this and try to avoid doing comparative studies as much as possible, because the studies that have been done show bright light therapy to be as or more effective than drugs, but with none of the side effects. Those are not the results that pharma companies who need to sell drugs want to see.

(09-01-2014 03:27 PM)el conquistador Wrote:  If I'm in the Northern Hemisphere during the winter I consider the blue-light a must. I might now look into light boxes.

You should -- I think you will see even better results from a high quality full spectrum box.

(09-01-2014 03:27 PM)el conquistador Wrote:  OP - would you bother if you were living near the equator?

Yes, like I said in the OP bright light therapy is not only for Seasonal Affective Disorder. It is a great tool in general for those who suffer from problems with their sleep, or with depression and anxiety, whatever the causes.

Two examples where I've seen it being very effective are:

1. Guys coming off shift work whose sleep schedule is all messed up. They can use bright light therapy to rapidly and effectively recondition themselves to a normal sleeping schedule.

2. Guys who have been hard drinkers and are trying to get away from that. They tend to have problems sleeping and also suffer from a kind of "drinker's depression". I've known a few of these and in a couple of cases they actually followed my recommendation of using bright light therapy, with great results.

Post: #6

So, maybe I'm missing something here, but what's wrong with just going outside and letting the sun work its' magic - the way it's been doing since inception.

Post: #7

(09-01-2014 04:30 PM)SteveCR Wrote:  So, maybe I'm missing something here, but what's wrong with just going outside and letting the sun work its' magic - the way it's been doing since inception.

Simply that by going outside you do not get a sufficient intensity of sunlight to have a therapeutic cuing effect that resets your circadian cycle. That is, of course, especially true during the winter months, but it's also true generally.

Here is an excerpt from the Columbia Q&A I linked to in the OP:

Quote:Is increased exposure to normal room light therapeutic, without the use of special apparatus?

Some very light-sensitive people, living and working in dim environments, may feel improvement with increased exposure to normal room light. Research studies show, however, that most sufferers of SAD and winter doldrums require exposure to light levels much higher than ordinary indoor lamps and ceiling fixtures provide. Such therapeutic levels are five to twenty times higher (as measured in lux or foot-candles by a light meter) than typical indoor illumination in the home or office.

If outdoor light intensities are what's critical, can the therapeutic effect be achieved by spending more time outdoors in winter?

Again, some individuals report improvement by spending more time in the sun. For most, however, the strongest therapeutic effect requires exposure to artificial bright light in early morning - at an hour (6:30 a.m., for example) when it is still quite dark outdoors during long winter nights.

I would also add that, as I noted in the OP, the optimal effect depends on consistency -- you want to expose yourself to bright full spectrum light every morning around the same time, shortly after you wake up to achieve the optimal effect in terms of entraining a consistent sleeping schedule and achieving the concomitant anti-depressant and anti-anxiety effects. You are not always able to be outside at a set time every morning, and you may not always have sufficient intensity of sunlight available (generally during the winter, and also on overcast/cloudy days). A light box provides you with a consistent 10,000 lux of full spectrum light same time every morning, day in day out, rain or shine. That is what achieves the best therapeutic effect.

Post: #8

I read into the topic and instead of wasting money on a nice gimmick, I think I will install some light bulbs with sufficient power and color.
See http://de.wikipedia.org/wiki/Lichtfarbe (google translator?) for the specific designation of light bulbs regarding, color temperature and color spectrum.
965 (6.500K full spectrum) only seems available as gas bulbs, 865 seems to be widely available as fluorescent bulbs.

If you have a daylight device, what is the designation printed on the bulb(s)?

The Philips HF3319/01 Energy Light (sold for >100€) uses 2 bulbs Philips PL-L 36 Watt 865, for a combined price of ~10€. They are not full spectrum.

Post: #9

When I learn about new things like this, I like to try to look at things first from a historical standpoint, then logical and then scientific.

So, let's look at historic. Let's go back in time to before the light bulb was invented, sometime in the mid 19th century. Would we have used light boxes? No. Did we have sleep, anxiety and depression issues? Probably so, but were these issues caused by the lack of a light box? Probably not.

So now let's move on to logical. Whenever I get to this part, I also like to compare human life to animal life. After all, we are animals, and it can helpful to observe animal behavior to learn about our own. Do animals in their natural wild habitat have sleep, anxiety and depression issues? Not that I'm aware of.

And lastly, comes scientific. I only do scientific research if whatever I am interested in passes the historical and logical tests, since research takes quite a bit of time.

There's a saying that I've come to have grown fond of: Nature is perfect, and you can not improve on it. Nature's own version of a light box works immaculately (the sun), and all creatures in the animal kingdom (humans included) have slept perfectly fine since our inception without the usage of a light box. Why do we suddenly need to use one to sleep well?

Post: #10

(09-01-2014 05:09 PM)void Wrote:  I read into the topic and instead of wasting money on a nice gimmick, I think I will install some light bulbs with sufficient power and color.
See http://de.wikipedia.org/wiki/Lichtfarbe (google translator?) for the specific designation of light bulbs regarding, color temperature and color spectrum.
965 (6.500K full spectrum) only seems available as gas bulbs, 865 seems to be widely available as fluorescent bulbs.

If you have a device, what is the designation printed on the bulb(s)?

void, light boxes are not a "gimmick". There are reasons why this design is to be preferred to just installing some fluorescent bulbs.

Here is a decent explanation:

Quote:WHAT IS AN APPROPRIATE LIGHT BOX?

The best lights for bright light therapy are fixtures containing white fluorescent light bulbs behind a diffuser, and tilted forward so that the light is angled downward, permitting more light to enter the eyes and decreasing the apparent brightness of the light, in turn creating less glare and improving user comfort. The diffuser performs two purposes: it spreads the light evenly over the surface of the unit, and it absorbs and filters out the potentially harmful UV rays. A variety of light boxes are available to meet individual needs, including large models on floor stands for use with exercise equipment, very compact models for frequent travel, and even models designed to fit into standard office decor.

While the critical factor in bright light treatment with a light box is the intensity of the light, full spectrum light with the UV-A and UV-B filtered out for eye and skin safety produces less glare than other types of lighting, resulting in greater user comfort.

In other words, you want to achieve a nice even glow (rather than the concentrated glow from a 5,000 lux bulb), you want the light to be coming at the right angle, and you want to filter out the UV component. All of this is achieved by the light box design.

Full spectrum light boxes are what has proven efficacy in research studies.

http://www.medscape.com/viewarticle/491504

Quote:Light therapy is as safe and effective as fluoxetine for the treatment of seasonal affective disorder (SAD), according to a Canadian randomized trial. Clinicians, therefore, should consider light therapy for patients who may prefer this modality, researchers report.

"It's always a struggle to bring nonpharmacological treatments into mainstream medicine," Raymond W. Lam, MD, FRCPC, FAPA, told Medscape. "...so, we try to stress that there's a very effective [nonpharmacologic] treatment out there for winter depression — light therapy, and it's a shame that more patients aren't getting access to it because physicians aren't aware of it."

Dr. Lam is a professor and head of the Division of Clinical Neuroscience, Department of Psychiatry at the University of British Columbia (UBC) and director of the Mood Disorders Clinic at UBC Hospital in Vancouver, Canada. He presented the results of his latest trial on the use of light therapy in SAD here at the 54th annual meeting of the Canadian Psychiatric Association.

The currently accepted light therapy for this condition is use of a 10,000 lux white fluorescent lightbox 30 minutes daily in the early morning, usually between 7 and 8 am.

Post: #11

Nevermind, I answered my own question with a small amount of research.

A light box is beneficial in the absence of sunlight, if you rarely get adequate sunlight. I would assume that most of us do not do this. Very interesting article, OP. I live not too far from the equator, and I get about 1-2 hours of sunlight per day, but I know plenty of people who rarely get sunlight at all.

Thanks for the article.

Post: #12

SteveCR, would you also not take penicillin to treat an infection because it was invented in the past one hundred years? Would you not use a car or even a bike because our ancestors did fine just walking?

Nature is not perfect, and human beings try to improve on it all the time -- that is what we do.

In reality, millions of people take huge amounts of potent drugs with sometimes devastating side effects in order to sleep better or feel less depressed. In this case, I am describing a therapeutic modality which has no side effects, and consists solely of absorbing full spectrum visible light, but at regular intervals and increased intensity to achieve the desired effect. There are few things that can be described as "therapy" that are closer to "nature" than that -- in fact, I cant really think of any.

Natural sunlight is great, don't get me wrong. And as I wrote in the OP, the light box is not a substitute for natural sun exposure, in particular because you need the UV frequencies to stimulate vitamin D production. But the evidence shows that you need a regular and consistent 10,000 lux every morning to achieve the best benefits in terms of a regular sleeping schedule and improved general function. So there you have it.

Post: #13

(09-01-2014 05:30 PM)SteveCR Wrote:  Nevermind, I answered my own question with a small amount of research.

A light box is beneficial in the absence of sunlight, if you rarely get adequate sunlight. I would assume that most of us do not do this. Very interesting article, OP. I live not too far from the equator, and I get about 1-2 hours of sunlight per day, but I know plenty of people who rarely get sunlight at all.

Thanks for the article.

You're welcome, but this is not really the correct conclusion. Bright light therapy can be beneficial to many people who are having trouble setting and maintaining a good consistent sleeping schedule, as well as people who suffer from anxiety and depression.

Again, the key is not just exposure to sunlight at any time. The key is to get sufficiently intense exposure at a consistent time every morning (shortly after you wake up). That is what entrains you to a correct circadian rhythm.

Finally, I'm not saying everyone should go out and get a light box. If you're sleeping well and have no problems with anxiety or depression, there is no need to do anything. This is for those who have a problem that needs to be addressed.

Post: #14

Great post, I'm definitely looking into buying one. How effective is it in combatting depression for people who already spend a lot of time in the sun, eat very healthily, juice daily and sleep well (i.e has an otherwise excellent lifestyle?).

Post: #15

(09-01-2014 06:00 PM)Cyr Wrote:  Great post, I'm definitely looking into buying one. How effective is it in combatting depression for people who already spend a lot of time in the sun, eat very healthily, juice daily and sleep well (i.e has an otherwise excellent lifestyle?).

I think it would still be effective, particularly in the fall and winter months (since you necessarily get less sunlight during these months, and you don't get a sufficient intensity in the morning when it matters most).

I would add that someone who is depressed to any appreciable degree almost never really sleeps well. It is almost a contradiction in terms, since virtually any state that rises to a level of appreciable depression involves some dysregulation of sleep. Of course you can sleep well and still be psychologically unhappy or frustrated, but that is really not the same thing as "depressed".

People who are depressed in a real sense (even mildly) tend to have bad sleep structure. Meaning, they might sleep for a normal number of hours, but the sleep will not be structured properly, and will often leave them groggy and downcast, rather than restored and refreshed, when they wake up. Bright light therapy would help improve the sleep structure, which is intimately related to the depressive state.

Post: #16

I improved my sleep my getting good curtains that block out the sun.

The early morning sun was waking me up prematurely. Keeping my bedroom as dark as possible allows me to stay asleep longer and better.

I also keep an empty 1 gallon jug near my bedside so that I don't have to walk to the the bathroom. Like this:



I just sit up to pee.

I need to go to bed earlier.

Post: #17

(09-01-2014 10:49 PM)Giovonny Wrote:  I improved my sleep my getting good curtains that block out the sun.

The early morning sun was waking me up prematurely. Keeping my bedroom as dark as possible allows me to stay asleep longer and better.

I typically wake up early, because the sun rises fairly early here in Costa Rica. I usually get up between 5am and 5:30am. I go to bed around 10pm. The sun sets around 6pm or so.

Post: #18

(09-01-2014 06:10 PM)The Lizard of Oz Wrote:  

(09-01-2014 06:00 PM)Cyr Wrote:  Great post, I'm definitely looking into buying one. How effective is it in combatting depression for people who already spend a lot of time in the sun, eat very healthily, juice daily and sleep well (i.e has an otherwise excellent lifestyle?).

I think it would still be effective, particularly in the fall and winter months (since you necessarily get less sunlight during these months, and you don't get a sufficient intensity in the morning when it matters most).

I would add that someone who is depressed to any appreciable degree almost never really sleeps well. It is almost a contradiction in terms, since virtually any state that rises to a level of appreciable depression involves some dysregulation of sleep. Of course you can sleep well and still be psychologically unhappy or frustrated, but that is really not the same thing as "depressed".
People who are depressed in a real sense (even mildly) tend to have bad sleep structure. Meaning, they might sleep for a normal number of hours, but the sleep will not be structured properly, and will often leave them groggy and downcast, rather than restored and refreshed, when they wake up. Bright light therapy would help improve the sleep structure, which is intimately related to the depressive state.

I wouldnt describe myself as seriously depressed, but mental illness (schizophrenia, extreme depression, paranoia etc) runs in my family and recently despite the fact that my life is going well/ improving I have been very 'down' and am lacking in enthusiasm.
I have not had problems with my sleep, but have (voluntarily), been going to bed v late during the summer and even though I get a lot of sleep, I havent really been properly refreshed. This problem should resolve itself anyway as I get into going to bed early again.

Anyway, either way, thanks for the post and I am definitely ordering a light box.

Post: #19

(09-01-2014 05:25 PM)SteveCR Wrote:  When I learn about new things like this, I like to try to look at things first from a historical standpoint, then logical and then scientific.
...

There's a saying that I've come to have grown fond of: Nature is perfect, and you can not improve on it.

I am stating this as a successful user of light therapy.

In the abstract philosophical sense, nature is perfect.

In physical reality, nature cares nothing for us and will ultimately totally destroy us and any memory of us. We battle this, but to no effect in the end.

Nature is completely indifferent to you.

We are so very very far from any sort of "noble savage" existence that the idea 99% of us could or will want to approximate any kind of "natural" existence ( hunter gatherer or subsistence farmer) is totally absurd.

Some of you are sharp enough to get location independent businesses going in 5 years or so and get out of the The Box, or The Pod as I like to put it; but it has taken me 20-25 years to be lying in the Phils on a Wednesday morning with the freedom to do whatever I want today.

What most of us have most of our lives is a very unnatural, enclosed life where we are exposed to too little natural light because our owners need us working all day in florescent offices.

We also get not nearly enough exercise distributed throughout day.

The majority of us are left with the situation of how to compensate for a totally, total unnatural lifestyle.

(09-01-2014 05:25 PM)SteveCR Wrote:  Nature's own version of a light box works immaculately (the sun), and all creatures in the animal kingdom (humans included) have slept perfectly fine since our inception without the usage of a light box. Why do we suddenly need to use one to sleep well?

You're being obtuse, the regularity needed and the intensity needed are already explained above as being hard to achieve in real life.

In our employment boxes, where the owners can watch us, we concentrate on a rectangular screen maximizing the returns on investment of our owners, until and unless we own our own businesses.

Most of our lives, most of the time, have nothing whatsoever to do with the perfect nature you imagine.

Also as a successful user of light boxes and a mental health worker, I can tell you nothing happens in health care without someone profiting.

Light boxes are so great because as OP mentioned, there are really no side effects, except for me a very slight transient headache if I overdo it.

Post: #20

(09-02-2014 05:35 PM)iknowexactly Wrote:  Some of you are sharp enough to get location independent businesses going in 5 years or so and get out of the The Box, or The Pod as I like to put it; but it has taken me 20-25 years to be lying in the Phils on a Wednesday morning with the freedom to do whatever I want today.

I like to call it The Bubble.

I agree with you. I have built the life that I desired, and I do tend to forget what it's like for people who are still slaving away.

Post: #21

(09-01-2014 10:49 PM)Giovonny Wrote:  I also keep an empty 1 gallon jug near my bedside so that I don't have to walk to the the bathroom. Like this:



I just sit up to pee.

I need to go to bed earlier.

Not trying to derail a quality thread, but if Gio ever starts a blog, there's a perfect title here:

"Piss Jugs and Day Game"

I already have a Canadian guest post ready to go too:

Post: #22

(09-02-2014 08:17 PM)LeBeau Wrote:  Not trying to derail a quality thread, but if Gio ever starts a blog, there's a perfect title here:

"Piss Jugs and Day Game"

Gio is obsessed with high quality sleep and 18 year old pussy.

That makes him a man after my own heart.

Post: #23

(09-02-2014 04:20 PM)Cyr Wrote:  Anyway, either way, thanks for the post and I am definitely ordering a light box.

Sounds good.

Make sure you get one which is full spectrum (not blue light or red light) and can provide 10,000 lux. Don't go for the cheapest models out there -- quality makes a real difference, and it's a one time investment. And most importantly, make sure you use it correctly when you get it -- same time every morning, shortly after waking up, for 30 minutes at 10,000 lux at the correct distance from the box (distance depends on the exact product and will be part of the instructions).

Post: #24

Do you have to have your eye open while this is running? I tend to wake up early to go to the bathroom than go back to sleep for a few hours.

Post: #25

(09-03-2014 12:32 PM)kbell Wrote:  Do you have to have your eye open while this is running? I tend to wake up early to go to the bathroom than go back to sleep for a few hours.

LOL, I think that is one of the most unlikely questions that have ever been asked! Kudos.

Yes, kbell, you have to have your eye open -- in fact, I'd be even so bold as to say you should have both eyes open . That is really the point here. Although there are many places in your body that have light receptors, the eyes are a pretty important one, unsurprisingly.

Also, using the light box and then going back to sleep completely defeats the purpose. The idea of bright light therapy is to cue your body and brain to start the diurnal cycle at the same time, shortly after you wake up. So the idea is that you wake up at the time you want to set as your day-to-day waking time, use the light box for 30 minutes shortly thereafter, and then start your day. Believe me, after 30 minutes of 10,000 lux (eyes wide open ) you will not be wanting to go back to bed -- you will be feeling awake and ready to start your day.

If your bathroom waking time is too early for you to start your day, you do the light box later. Again, you want to entrain yourself to wake up at around the same time every day, and you use bright light therapy to (among other things) entrain yourself to that time by always doing it at the same time which is shortly after your desired waking time. If you do it for a while, you might find that your sleep structure changes and you no longer even have the early bathroom waking.