Couldn't do it today as I decided to attend a class in the evening. Since that was in London at 6.30 I could not take a nap. So, decided to go monophasic just for tonight and following the advice from the forums added 1.5 to my intended biphasic sleep (i.e. 6.0 + 1.5 ), total 7.5 hours sleep. Got up at 8.30 am this morning, therefore, and it worked very well as I felt fresh all day. Will resume the biphasic efforts from today.