Al has Parkinson's and he started using a two-wavelength Duo Coronet in July last year, once daily in the morning.

I had an email from Al the other day, and I have his permission to quote his very interesting comments.

'If I miss a day session, there is a gradual change in me. Bad dreams come back, my tolerance level goes way down and my lethargy goes way up.'

'I have noticed that on the occasions I have missed just one day of the Coronet that it takes three days of use to put me back to where I was before.'

Three days. That is the first time anyone has quantified the experience of stopping using lights and then resuming them. It is consistent with the comments others have made. Three days!

Al has been doing battle with a bung knee and finally had a knee replacement in November of last year, spending a number of days in hospital.

'I didn't use the Coronet for about four days and my perseverance with recovery exercises plummeted. When I reinstated the Coronet I started to self-motivate the exercises and my recovery accelerated to be in front of the expected recovery schedule.'

Parkinson's is, as I've often said, a slippery and tricky disease. It often robs a person of the ability to have insight into what is happening in the mind and body. Al is unusual in that he is very aware of changes, plus he has the wonderful Barb to pull him in line when needed.

'If I forget [to use the Coronet], Barb notices a difference and reminds me.'

Al 's most recent specialist appointment concluded that his Parkinson's is stable. He said 'I am convinced that acceleration of symptoms is being kept at bay.'

Al's summary is really helpful in reinforcing some key aspects of using transcranial red and near infrared light (whether DIY or the Coronet):

·         use it daily - my own feeling is that twice is better than once;

·         the odd day off is OK, but aim to use it every day;

·         think of the light hat as being like the brain equivalent of cleaning your teeth; and

·         like cleaning your teeth, it is forever.