Recently (this year, actually), I am getting MUCH higher “deep” sleep percentages. According to the received knowledge of sleep specialists, there are TWO stages of lighter sleep. One is a gentle drifting off or going back to sleep after awakening, or after intense dreaming that doesn’t necessarily wake you. That’s light enough that it’s very easy from which to awaken. The next stage is a deeper level of sleep, but not true slow, Delta wave sleep, which is usually a small but significant part of your sleep. It’s so important that we would like to know when we are not moving, not twitching, and not even dreaming. The body is healing itself. This represents about 20%-30% of your night, tops. The other, lighter stage of real sleep, is apparently being combined with the deepest sleep in the SaA graphs. Or that’s a good guess judging by the fact that 30% to 70% of sleep is considered “deep.” If an extra stage between ultralight and deep sleep can be determined from the available data (HR, probable REM, etc.), perhaps it can gather the “less than slow wave, but more than truly light” sleep.
Do you think this is possible? Because that intermediary stage is most of your sleep, and also plays a part in sleep disorders, when sleepers get trapped between non-slow wave and slow wave deepest sleep.
There are a variety of these disorders and I experienced both childhood night terrors and late adolescence night terrors (16-24 years old, after which it seems you actually “grow out of it” as your sleep pattern changes from adolescence to full-on adulthood.) The non-childhood forms of night terrors are often remembered vividly as truly being unable to communicate with another person while even getting up, walking around in a daze, trapped between sleep stages. It’s a close cousin to sleepwalking and sleep paralysis, although one is partially awake in late adolescent night terrors. A truly horrible experience! I literally grew out of it by age 25. Also, keeping the room dark and noise-blocked helps tremendously. My last night terror happened with the lights and TV blaring during a Perry Como Christmas Special. (I am dead serious: he put me to sleep, and then something awakened me between almost reaching deep sleep while in semi-light sleep.)
Due to these disturbing disorders, it would be helpful to watch your descent into the deepest sleep, with correlations between symptoms and light & sound levels, which are keys to prevention along with minor medication. We’re talking about sleep-walking, sleep paralysis, at least 2 different kinds of night terrors (particularly according to age), seriously disturbing nightmares, periodic limb movement, Restless Legs Syndrome (which sleep stage precceded an awakening attack of RLS? Truly Deep/Slow Wave, or “Light 2”? That could help doctors advise as to prevention and prescribing.). Millions of people suffer from these sleep disorders at different times of life.
Thanks in advance for putting this on the “for future consideration” list.