Arsenal chief executive Vinai Venkatesham says he has had sleepless nights over recent staff redundancies.     The club were criticised for buying players shortly after announcing 55 redundancies - mainly affecting the commercial and administrative departments - on 5 August.   Senior staff, including manager Mikel Arteta and his players, took pay cuts.   "I would be lying if I said there had not been sleepless nights," Venkatesham said.   Nine days af