Robin Williams' widow has claimed the couple were told to sleep separately by his doctors before his death.

The iconic actor took his own life in 2014, and was suffering from poor mental health, insomnia, and Lewy body dementia - a type of brain disease that affected his thinking, memory and movement control - prior to his passing.

And his widow, Susan Schneider Williams, has now claimed she wasn't able to sleep in the same bed as her spouse in the months before his death, because doctors had ordered them to sleep separately in an attempt to help ease Robin's insomnia.

Recalling the ''hard'' decision to sleep in a different bedroom to Robin, Susan said: ''He said to me, 'Does this mean we're separated?' That was a really shocking moment. When your best friend, your partner, your love - you realise that there's a giant chasm somewhere, and you can't see where it is but that's just not based in reality. That was a hard moment.''

Robin's battle with Lewy body dementia is the subject of a new documentary titled 'Robin's Wish', as his loved ones didn't find out about his condition - which is the second-most common type of progressive dementia after Alzheimer's disease - until years after his death, because he was misdiagnosed by doctors.

Susan added: ''Robin and I knew there was so much more going on. Robin was right when he said to me, 'I just want to reboot my brain.' In that moment, I promised him that we would get to the bottom of this. I just didn't know that would be after he passed.''

Susan also remembered her spouse - who was 63 when he died - as a man who was ''versed in so much about humanity and culture'', and who just wanted to make people happy.

In an interview for the 'Today' show, she said: ''This was a man who was incredibly rich and deep and versed in so much about humanity and culture, and his humour was like this secret weapon. There were so many times when he would see someone needed a lift, and then he would just inject a little bit of humour in just the right way to make a difference.''