What defines the easiest time to get out of bed in the morning for humans? I'm interested in sleep research, and sometimes in conversations with people the following idea gets discussed: "A person becomes aware at a certain time in the morning and feel great(while still in bed). But the wake up time is later, so that person keeps sleeping and the feeling is gone. It's much harder to get out of bed". The general pattern is that there's a perceived good time to get out of bed, but people oversleep it.

From my understanding, the second part of this statement is caused by sleep inertia, where a person slips into deeper sleep(slow wave sleep SWS) stages. But what about the perceived "perfect wake up time"?


What sleep stage or sequence of sleep stages, if any is associated with this feeling of energy in the morning(NREM1,2?)?
is this feeling associated with light exposure (ex: 20 minutes after light exposure)
does it happen every day, for all people?
Is there some " deep sleep hormone" (probably not melatonin) that gets released in deeper sleep stages and produces sleep inertia?


There are a couple very successful sleep apps for smartphones that are marketed for this principle (they advertise the ability to find this "best wake up time" for you) and hundreds of imitations ("smart alarm clocks"). But is there really a phenomenon like I'm describing above, or is it a rare glitch of the endocrine system or something?
Human sleep has an (approximate) 90 minute rhythm: about every ninety minutes you are in light REM sleep. When you wake up while in REM, you wake up refreshed. If your alarm clock is set 30 minutes after your last REM phase, then you are in deep sleep again, and, although you slept longer, you will awake groggy and tired. The solution is to get up a bit earlier and feel a lot better.

As the comments suggest, there are some appliances to wake you up during an REM phase. From my experience, all you need is an alarm clock and go to bed early enough to catch enough sleep: after getting up at the same time for a couple of weeks, you'll start waking up in an REM phase before your alarm clock goes off. Just get up and don't go to sleep again, if your clock shows you are within 45 minutes of your alarm time, and keep doing so for as long as you want to keep this rhythm. Keep to the rhythm on weekends, too, for at least a month. If you feel you have fixed it, you can sleep in on free days – or rather, wake up at your usual time but stay in bed and go to sleep again.

Regular sleep (same get-up times each day) are the solution for most sleep related problems. Only when you get up regularly, can your body find and signal the ideal length of nightly total sleep. There is a huge difference between seven days of regular sleep, and six days of too little and one day of too much sleep, even when both add up to the same total length. And yes, I did not write "go to sleep regularly". What you need to do is get up regularly. Your body will tell you when you need to go to sleep, and this will vary, depending on the day you had. All you have to do is listen to it, instead of finishing that movie. Healthy sleep needs discipline, or the absence of electricity.



Sources:

No research on this, just personal experience and lots of similar anecdotes on the web. For the 90 minute sleep pattern, pick up any textbook on biological psychology, e.g. Pinel, J. P. J. (2011). Biopsychology (6th ed.). Pearson, and read the chapter on sleep.