Scared of the dark?

I am at my wits end with Sienna, she is STILL waking 4-5 times a night and grizzling despite letting her CIO. She's got the message that crying doesn't get her anywhere coz she's given up on the constant screaming that she was doing a few weeks ago, now she just wakes and grizzles and grouches and rattles the bars on her cot. I can doze thru it but it's stopping me getting a decent sleep which I really need right now!
When she first starts up I go in and check on her to make sure she isn't sick etc. (just in case, even tho I know she is fine), then I leave her to it, she usually screams for about 10 mins then goes quiet but an hour or so later starts all over again.
Mum suggested this morning that maybe she is scared of the dark? So she wakes up and is scared? Would explain why she is fine when I go in there and why she seems to wake around the end of each sleep cycle.
What do you guys think? Is it worth trying a night light? They have their Grobag egg but it doesn't give a lot of light. My only worry is that if it's NOT a fear of the dark, having a nightlight on might make the problem worse?

I'd give it a go too.  Try it for a couple of nights and if it doesn't make any difference take it away again, they'll get used to not having it pretty quickly.

You can get the plug in light sensor ones from the warehouse pretty cheap, they turn themselves on when it gets dark which saves you from having to remember to do it.

We stopped a lot of Isla's night waking by cutting out cheese from her diet,...nautropath told us that its toxic to the liver and was problem causing nightmares,...we cut out that and a few other things for other reasons tho,..and she tonnes better.

Thanks! Will save me buying one, it's not the $$$, it's that I can't be bothered going shopping!