Sleep muscles: three measures to check if you still feel exhausted

Experts say sleep quality—not just duration—can explain feeling tired after seven or eight hours, and they highlight three measurable areas to watch: sleep latency, time in deep sleep, and sleep efficiency.

Many people report waking tired despite getting seven or eight hours of sleep, and experts say total time is only part of the picture. A 2026 study from Vitality and the London School of Economics and Political Science is reported to link consistent, good-quality sleep with longer life. Sleep specialists emphasize three measurable aspects—sleep latency, deep sleep time, and sleep efficiency—that influence whether sleep is restorative. The article summarizes expert observations about these measures and reports approaches that may support them. Key points: - The 2026 Vitality-LSE study is reported to link consistent, high-quality sleep with as much as four additional years of life. - Experts describe three "sleep muscles": sleep latency (how long it takes to fall asleep), time spent in deep sleep (restorative stages), and sleep efficiency (the share of time in bed actually spent asleep). - Sleep latency regularly above about 20 minutes is reported as an indicator that circadian timing may be off. - Most adults are reported to need roughly 60 to 90 minutes of deep sleep per night for physical restoration. - Fragmented or interrupted sleep reduces sleep efficiency and can leave people feeling exhausted even after long periods in bed. Summary: Together, these measures determine how restorative a night’s sleep is and relate to daytime energy and longer-term reported outcomes. The article notes that experts describe environmental adjustments, a steady nighttime routine, and a consistent sleep schedule as ways to support sleep latency, deep sleep and efficiency. The article also reports that medical evaluation may be appropriate if symptoms such as snoring or pauses in breathing are present.