Modern smartphone apps offer this information. A smartphone has a gyroscope built in, and when you lay it on the mattress close to your body, it picks up tiny movements. As you fall asleep, your musculature relaxes, and the app knows how to distinguish the movements of a person in deep sleep, light sleep, and lying awake. It provides you with a record of your sleep cycles for the night.
It is probably not perfectly accurate, but I find it quite good from personal experience. It certainly can distinguish between times when I lay awake, trying to fall asleep (and not noticeably moving) and times when I am really asleep. I can't say how good it is for hypnogogic states, and it can be fooled somewhat if you are concentrating on not moving while awake (e.g. if you are doing a muscle relaxation exercise or meditating). But for normal sleep, it gives you a nice record.
I have no peer reviewed sources on this, so will have to give you a commercial link: Sleep as android is the app I use, but AFAIK there are several per platform. If you have a fitness tracker such as Fitbit, it might offer a similar functionality - there are headbands specifically for sleeping, probably more accurate than a smartphone (but also more intrusive).