Hi Garry

I stumbled across your post while googling PhD opportunities in sleep so thought I'd add my thoughts.  I work in a sleep centre near Cambridge and find myself in a similar situation - I'm 26 and have been considering doing a PhD but have similar concerns.   I love my job so wouldn't want to leave so would but I also feel it is important for my future career and I'm worried that without it I might reach a ceiling without it.  It's great to hear you are happy with life as things are and perhaps that stops me doing one in the other way as I realise that doing a PhD will stop me living the life I want for the next few years. 

Do you mind me asking which university you are considering? I'm currently looking into where I could apply to if I did decide to pursue it so I know what my option are.  Have you thought about doing a MSc or MPhil which would be a half-way option that could be done part-time and possibly staying in your current job?  I think this is the way I might go as I feel I will need some form or postgraduate qualification if I want to pursue a career in research but doesn't mean quite the slog.  You can always then progress this to a PhD if it suited you. It's also quite scary even considering giving up something you enjoy especially knowing how difficult it might be to find a job afterwards.  I'm not sure if you would be eligible for NIHR Research Fellowships which would fund the tuition fees and also research costs but its something I've looked into as I could stay in my job (I work in the NHS).   

Good luck with your decision...my advice would be to speak to as many people about it as possible to get different perspectives.  It probably doesn't make it much clearer (it even confuses things at times) but at least you can make the best decision for you!

Becky