Fitbit Flex is the sleep tracker i use and it is the tracker I will use in all of my sleep case studies. I got mine on Amazon for around $90.00. Fitbit flex wristband does a lot more then track your sleep , like track your steps, record your eating habits, recording your fluids you drink. How much exercise you did this week and weight goals. All though I have had troubles staying asleep, I have never had troubles getting to sleep. or getting up. With fitbit and as you can see with the images to the right.(Note: Image button above will show a larger size of each image) I have a 91% sleep efficiency which is really good. But it did not start out that way. There was a few things that kept me awake. Drinking to much water before I went to bed resulted in me getting up every 2 hours to use the bathroom.