SHHS MOP 6-626-mop-rules-for-assigning-sleep-stages, Deep Sleep (Stage 3 and 4) use a more concise definition for delta wave used for deep sleep, “delta waves which are < 2 Hz (duration 0.5 s.)” more concise definition would be “delta waves which are 0.5-2 Hz (duration 0.5-2 sec)”
https://www.sleepdata.org/datasets/shhs/pages/mop/6-626-mop-rules-for-assigning-sleep-stages.md
SHHS MOP 6-626-mop-rules-for-assigning-sleep-stages, Deep Sleep (Stage 3 and 4) use a more concise definition for delta wave used for deep sleep, “delta waves which are < 2 Hz (duration 0.5 s.)” more concise definition would be “delta waves which are 0.5-2 Hz (duration 0.5-2 sec)”