Be aware that SAD light therapy is dealing with the symptoms of Winter depression and not the cause.

If next year you enter the winter with a 25(OH)D status above 60ng/ml =150nmol/l and you take 1000iu/daily for each 25lbs you weigh you will I am sure (well if my experience is anything to go by and as the research shows) you will be less likely to experience winter depression. Depression results in brain inflammation, ensuring Vitamin D3, omega 3 and magnesium levels are optimum provides your brain with ample reserves of anti inflammatory agents so it is better able to deal with the inflammation and resulting depression.

Indeed bright light therapy does help reset the circadian rhythm but IMO it's better not to be depressed than treat the symptoms however successfully.
Full Spectrum applies to the VISIBLE light waves so SADLIGHTS (of every make) do not produce UV light so you won't get a tan, you won't get skin cancer, you also won't increase your vitamin D3 status. UVB radiation is required for vitamin D3 production but too much UVB burns the skin cells. If you look directly at a UV light source you damage your eyes in the same way that looking at the sun directly for more than a few seconds could cause irreparable damage.

Because these lights do not provide UV radiation they cannot and will not affect your vitamin D status. All they are doing is acting on the pineal gland to stop the production of melatonin in the morning and having a bigger contrast between DAY and NIGHT helps reset the internal body clock. They are also useful for treating jetlag.

When using sadlights it's helpful to make sure your bedroom is pitchblack at night and you don't have any nightlights or digital displays or street lighting and if you have to get up in the night DON'T put the light on. The darker the room the more melatonin will be made.

Thx again Ted,

Ok its back to one 50,000iu per week for 8 weeks, then 5,000iu per day for me...am definately insuff vit D then...

Actually my bedroom is pitchblack - 2 layers (just to be sure) of blackout rolldown curtains.......i can't sleep at all even with any tiny bit of light in my bedroom...even if sunlight/streetlight shines through sides of blackout roll thing...had to cover the sides aswell...need extreme pitchblack to sleep...
which is abit wierd since i'm now taking vit D/sun pills???

i did consider taking a melatonin test but can't find one in uk....oh well thats uk..

Ok im new to all this but.. i want to test my vitamin D levels.. and maybe all my vitamin levels.. its possible to do this at home instead of going to the doctor? do I still have to draw blood? how do these home tests work?

Thank you

If you go to the Grassrootshealth website and sign up for a test (remember they are a charity promoting vitamin D awareness and trying to further Vitamin D research) . You complete a simple questionnaire they post you a test kit.
This consists of a sample collection tissue and a spring loaded lancet that pricks your skin.
you allow a largish drop of blood to form and allow this to drop onto the circle marked on the sample tissue. You repeat with another drop of blood into the second marked circle. Allow samples to dry write your Participant ID on the back of collection strip, then return in the envelop provided.
You will get an email in a few days telling you to logon to read your results.

How to Collect a Blood Spot Test Kit Sample This video shows how it works in practice. However for 25(OH)D just 2 drops are required.
I found I need to warm my hands first (good wash in hot water) and maybe whirl arms round a bit to make sure the blood is flowing well to the extremities. You can "milk" your finger a bit to get a big drop.

Full ZRT blood spot tests measure these items so won't be suitable for finding out your Vitamin A C E or other vitamin/mineral levels.