SAD light location and use for programmers? - eviltoast

It’s been a grey winter, and looking to stay that way. I work remote, so I was thinking of getting an SAD light. But I remember from years ago when I had one (and worked in an office) that if I put it next to my monitor it gave me a headache and made my monitor hard to see. Those of you using SAD lights, where do you put them, how long do you use them per day and all that?