Properly tracking your sleep can yield lots of information for both you and your treatment provider. Whenever I see a patient in my practice, I always ask that the patient fills out a sleep diary for the two weeks before we meet (I mail or email them the diary to fill out). I also have my patients continue using the sleep diary throughout treatment to see how simple changes can result in drastic improvement in the quantity and quality of their sleep, as well as increasing daytime energy.
There are many types of sleep diaries and a simple Internet search can even be confusing. There are even smartphone apps that have sleep diaries. However, it is extremely easy to keep a log yourself, and I have many patients who track their sleep in a journal or even on their phone. Figure out the best method of data collection for you and stick with it.
The best sleep diaries contain basic information about both the day and the night. They should take 1-2 minutes to fill out and in no way should increase stress levels and frustration about the bed. They should be brief so you can see the data and make any associations possible without sifting through paragraphs.