He has also complained of health problems and a drastic loss of weight since being imprisoned in a strict regime penal colony.
Prosecutors have requested Navalny serve his additional sentence in an even more restrictive, special regime prison.
In April, Navalny said he could be tried separately on terrorism charges and could face life in prison.
His campaign offices across the country were designated extremist organizations by authorities in 2021, putting staff, volunteers and supporters at greater risk of prosecution.
In the summer two heads of regional offices, Lilia Chanysheva and Vadim Ostanin, were sentenced to seven and a half and nine years respectively on charges of extremism.
Thousands of Russians have been detained for protesting against Moscow’s crackdown on Ukraine, and some of the most high-profile activists are now behind bars, including Vladimir Kara-Murza and Ilya Yashin.