Tangentially related, I got an androv full-spectrum lamp several years ago for some color work. It was one of the few true "full spectrum" bulbs you can get for cheap which are decently balanced without resorting to use a combination of bulbs. And yes, we tested it with a spectrometer.

Most other full-spectrum lamps I tried at the time on amazon didn't get even close.

If you never tried, working with these lamps is weird: turning it on in the evening or night by mistake _really_ wakes you up.

So yeah, I hope Androv kept up with the quality.

Maybe I should replace my daylight lamp with this, to counter the winter depression. (Norwegian).

Was that the desklamp? Do you happen to know a more specific model of such a lamp?

Yes, to be specific the 42W model. I did the order in 2010, to be specific, so some time has passed since I did the tests.

>... now more like every other day or every two days.

Can I ask the difference? I'm assuming a typo, but haven't experienced sun shortage for at least six years, so I'm not sure on boom / bust cycle potential with these things.

I dont understand the question. The difference between using every other day or every two days?

Using every other day = use one day, then not use it the day after.

Using once every two days = use one day, then not use it the day after.

Perhaps you meant "once every three days", i.e. use it one day, then not use it for two days?

Yes I meant every three days

Are these lamps safe?

A few applications à 15 min with a mercury high pressure lamp with a good reflector and you look like you went to the Caribbean for holidays. Maybe add a filter for UV-C, but there is no ionizing radiation. Just show any lamp in question to your favorite dermatologist. If he seems unhappy, you have the chosen the right lamp.

Jokes aside, skin is very photo-active and I do think lamps can help greatly against these kind deficiencies.

Most lamps emit a line spectrum though, so it is not like real sunlight. I wonder if that is the reason people going to solaria often seem to have weird skin tones. Ask a dermatologist and don't forget eye protection.

Apart from that it has the same side effects as sun exposure. Too much leads to skin aging, sunburn, cancer, etc.

Those side effects can be mitigated or at least reduced by adding extra infrared or red light. Eg sunburns are prevented or greatly reduced by treating with near infrared either before or after UV exposure.

Could you explain please how/why IR helps with sunburn? :o

There are some interesting papers turning up if you google „pubmed infrared sunburn“. One of these: https://link.springer.com/article/10.1007/BF00373376

Do you use it only in winter, or year round?

Year round