Is it advisable to use derma rollers at home for treating hair loss? If so, what is the optimal needle length, procedure?

Although there is some anecdotal evidence to support the use of microneedling(derma rollers) there is no solid clinical evidence at present to support its use.However,if you are still interested I would recommend consulting with a Dermatologist or experienced Hair Restoration surgeon.

IMO, derma-rollers have two impacts: First, if you use it with a topical agent such as Minoxidil, you may get better penetration meaning a higher blood level. Second, each prick is a small wound which attracts platelets to the wound site. The platelets contain wound-healing growth hormones that stimulate stem cells which, in turn, foster hair growth if hair bulbs still exist.  In effect, derma-rolling may be an inexpensive form of PRP therapy.  This form of treatment is also popular with face rejuvenation centers with reportedly good results.    

I'm still not sure if dermarolling as a sole treatment does much. However, I do think that there is emerging evidence that dermarolling with minoxidil may lead to better outcomes - at least in preliminary studies. Now how often and what size needles is open to debate. A 2013 research study of 100 patients supports benefit of dermarolling. The study set out to determine in patients who use topical minoxidil (Rogaine, etc) could achieve even further benefit by dermarolling.

In the study, 50 patients received daily minoxidil and 50 patients weekly dermarolling sessions (using a 1.5 mm dermaroller) in addition to minoxidil treatment.

Results showed that patients using a dermaroller achieved greater benefits than those using minoxidil alone. Specifically, 82 % of patients receiving dermarolling felt they achieved greater than a 50 % benefit in their hair compared to just 4.5 % receiving minoxidil alone. Physicians rated the improvements similarly. 

Hair counts (at an up close level) were increased in the dermarolling group compared to the minoxidil alone group (91.4 vs 22.2 respectively). 

Conclusion: These studies support the potential benefit of dermarolling - especially to enhance the efficacy of minoxidil. More studies are needed to verify or refute these results are well as to determine the optimal parameters for dermarolling. These include comparisons of daily vs weekly vs monthly treatment and comparisons of 0.5 mm needles, 1 mm or 1.5 mm needles. Studies are also needed to determine if patients any proportion of patient actually worsen with dermarolling.

Reference

A randomized evaluator blinded study of effect of microneedling in androgenetic alopecia: a pilot study.

Dhurat R, et al. Int J Trichology. 2013.

using a dermaroller to your scalp can actually damage your hair and make hair loss worse, I've seen in a lot in patients. I advise against it.

Thjere is no evidence that a derma roller does anything to help people who have hair loss. People who use this are on the wrong track. See a good doctor