Total sleep time isn't the key; watch deep and REM sleep

The article reports that sleep scores and how rested you feel depend more on time spent in deep and REM sleep than on total hours. Experts cited give typical stage targets (about 1.5–2 hours of deep sleep and roughly 1 hour 45 minutes to 2 hours 15 minutes of REM) and note habits linked to better stage stability.

Many people aim for eight hours of sleep, but the article reports that total sleep time may not be the main determinant of a higher sleep score. After a year of using commercial sleep trackers, the author found nights with more deep sleep and REM sleep produced better scores even when overall hours were shorter. Neuroscientist Ariel Garten, functional practitioner Conny Wade, and internist Dr. John La Puma are cited to explain why sleep architecture — the mix and continuity of stages — matters for recovery and mood. The piece also summarizes commonly cited stage-duration ranges and the habits experts associate with stronger deep and REM sleep. Key points: - The author observed that higher sleep scores followed nights with more deep sleep and REM, rather than strictly longer total sleep time. - Experts cited recommend about 1.5–2 hours of deep sleep for adults (roughly 13%–25% of a 7–9 hour night) as a benchmark reported in the article. - REM sleep is reported as concentrating in the second half of the night, with a commonly cited healthy range of about 1 hour 45 minutes to 2 hours 15 minutes. - The article notes deep sleep is concentrated in the first half of the night and that sustained, unfragmented slow-wave activity indicates higher-quality deep sleep. - Experts in the piece link certain factors to improved deep and REM sleep: morning outdoor light exposure, sleeping in a cool bedroom (about 60–67°F reported), and maintaining consistent bed and wake times. Summary: The article frames sleep quality—particularly the amount and continuity of deep and REM stages—as more consequential to sleep scores and daytime restoration than raw total hours. It reports typical stage-duration ranges and highlights environmental and timing factors experts say are associated with stronger stage stability. Ongoing tracking and research are presented as the context for how consumer devices and scores are evolving.