Should I sleep less to achieve my thesis targets?
Reducing sleep may work for a day or two. However, after that, sleep debt accumulates, and sleep deprivation will lead to a reduction in productivity.

Sleep is essential for your physical health, and in particular, it is essential for mental functioning. You may find it better to view sleep as a form of "work time". The cognitive structures you have about your thesis will be refined and pruned while you sleep. You'll make novel connections while you sleep. Sleep will also enable you to have the mental energy to engage in focused activity on the thesis. 

In particular, the kind of deep creative thinking required to analyse data and write a thesis is helped greatly by being well-rested. Sleep also helps ensure that the work you do is directed towards your goals. 

Thus, allocating enough time to sleep so that you are well-rested is essential to overall academic productivity.

So in general, if you are looking to maximise productivity in the medium-term (i.e., from a week or two to perhaps a month or two), then look at things other than sleep and thesis-time that can be trimmed. If possible, remove all other work commitments (i.e., no tutoring, RA work, consulting, etc.). Other work consumes largely the same set of limited mental and time resources that you have available each week. If possible, reduce non-work commitments. 

Also, in the medium term, many people do pull back from social and leisure activities a little bit. But in the longer term, you want to think about a balance to your life that truly works for you. I also think that incorporating at least a moderate amount of physical exercise is also important.