Sleep is important. The easiest way to see its value is to deprive yourself of it and to watch your skills and cognitive abilities erode. If I figured out how to sleep better, would I be able to supercharge my abilities to do anything? How could you measure it?
With the FitBit Alta you get some cool sleep data, specifically how much time you were Awake, REM, Light and Deep sleep. According to FitBit, it “your device tracks the beat-to-beat changes in your heart rate, known as heart rate variability (HRV), which fluctuate as you transition between light sleep, deep sleep, and REM sleep stages”. But…how accurate is it?
While the exact phases were not a direct match, the total amounts in the various phases were pretty close. Here’s the output of the sleep study from REM Diagnostics:
Page 4 (from Day 2):
Comparing my Sleep Study data to the data from both FitBits:
|Minutes in each stage||Average FitBit user||My FitBit average||My FitBit median||Sleep Study||FitBit 1||FitBit 2|
|Light (N1 + N2)||232||319||323||302||280||282|
|Deep (N3 + N4)||73||49||50||51||18||20|
|REM + Deep||168||127||129||117||99||111|
|Light (N1 + N2) %||58.0%||71.6%||71.4%||72.1%||73.9%||71.8%|
|Deep (N3 + N4) %||18.2%||11.0%||11.0%||12.2%||4.7%||5.1%|
|REM + Deep %||42.0%||28.4%||28.6%||27.9%||26.1%||28.2%|
Arianna Huffinton’s sleep book The Sleep Revolution was interesting but really only addressed why sleep is important and didn’t offer much in terms of how to sleep better. Shawn Stevenson’s book Sleep Smarter was probably the best sleep audiobook I’ve found so far and was pretty actionable.