Thanks for both replies they were very helpful.
I expected the Elonex to sleep, but if I haven't used it for a while I have to press the power button to start it again. There is a little progress bar at the bottom of the screen and it goes through a process that I can only describe as booting.
I think Elonex is a UK brand and a couple of its eReaders are commonly available in the UK. I paid £70 for mine which is good value in the UK.
If you are interested here is a link to a review
http://ebookreaderz.co.uk/ebook-read...reader-review/
Apart from being cheap it is very light and the battery seems to go on for ever and it reads ePub.
I think I will keep it for a while, but I am sure I will change it eventually for an eReader that sleeps.