Seyed, what is the intended purpose of the stimulation? The Limoge stimulator, for instance, is used to induce electrosleep, so there is no inherent inconsistency between transcranial stimulationa and sleep.

http://www.sciencedirect.com/science/article/pii/S0165027013002549

Hello,

The main purpose of this stimulation is to stimulate the vision region of the brain and analyze the resulted EEG signals.

But my main concern is that i have used previously mentioned methods (TNS & TMS & TACS) and unfortunately the pain that caused by these methods made patients awake.

So i need a system witch stimulate the vision region of brain, almost painlessly that would hopefully prevent the patient from waking up.

Thank you, 

Sincerely yours

Hi

check  this. hope it helps

Have you considered directed electro-magnetic pulses? I don't know of off-the-shelf products but I'm sure researchers in physics would know.

We have seen significant effects using subliminal TACS. I don't know that you would need to use sufficient current to cause discomfort. In fact, our subjects quite often fall asleep with the stimulation on.

what model/brand of stimulator you have used during your studies?

Hi! I am struggling with this issue too. There are few papers where subjects are stimulated while sleeping, and they usually use TACS or TDCS:

http://www.nature.com/neuro/journal/v17/n6/full/nn.3719.html

http://www.sciencedirect.com/science/article/pii/S1053810013001098

And there are classic studies using TMS (check related citations):

http://www.ncbi.nlm.nih.gov/pubmed/17483481

If you only want to give a one time pulse I think TMS would be the best option, there is a small sensation in the scalp, but you could try lower intensity to avoid it. I think the main issue with TMS is to correctly position the coil while the subject is sleeping. You should try to use earplugs in your subjects to avoid the sound. I dont know in which sleep stage you are trying to stimulate, but the arousal threshold is an issue; N3 would be the best time to stimulate.

tDCS would likely have the smallest negative effect (little or no pain) for what you want to do.  The main problem is that the electrodes cover a rather large area.  One advantage is that you can get the instrument for as little as USD 400.

They are stimulators that are licenced, not sold, as part of a therapeutic package. Since the stimulation parameters are limited to predetermined programs, I don't think they would be useful for you.

Sean, what does your "they" refer to?  Not certainly tDCS, since my program bought one a few months ago.

Have you consider using anesthesia?

Sorry, Gonzalo, I wasn't clear. The stimulators that I used were part of a therapeutic package. There are a huge number of manufacturers of tACS and tDCS, we used the one from NET Device Corp.

If they wake up due to the tactile sensation caused by the current, then if you can get a protocol approved, my best bet will be to apply a local anesthetic gel under the electrodes. 

I know previous literature where people have used EMLA (emulsion preparation containing 2.5% lidocaine and 2.5% prilocaine by weight).

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3026574/

That's a useful thing to know.