Filling out the SomniLog can be challenging. Some readers avoid it completely. Fortunately, you can still practice most of the techniques described in the SomniSkills Workbook without completing a SomniLog.1
Still, the SomniLog provides a valuable understanding of your sleep patterns. For that reason alone, we urge all readers to complete as much of the SomniLog as possible, even if for only a few nights. Completing the SomniLog also enables you to perform Sleep Episode Rationing, one of the most powerful SomniSkills techniques.
Smartwatches may be helpful in filling out the SomniLog. They have improved over the past few years and seem to be doing a better job at monitoring a person’s sleep.2 Anyone struggling to complete the SomniLog should consider using a Smartwatch to assist them. Although the comments below are based on using an Apple Smartwatch (Series 9), many of these suggestions are likely to be applicable to other Smartwatches that monitor sleep.
—————————————————————————————————————————–
As explained below, I cannot rely completely on my Smartwatch to complete the SomniLog. But it does make filling out parts of the SomniLog much easier. Here are my impressions of how a Smartwatch might help you complete the following items:
- Sleep Onset Latency (SOL) — The Apple Watch does not calculate SOL automatically. But it provides the data needed to calculate it. Each night you must write down when you close your eyes to begin sleeping (lights out time). The next morning, the watch will tell you when you fell asleep. The difference in time is your SOL.
Without a Smartwatch, it is hard to know how long it takes to fall asleep. On the other hand, based on my experience and research3, the Smartwatch data is pretty accurate. And it is much easier than trying to figure it out yourself.
However, there are two things to be aware of when using the Smartwatch to determine your SOL:
- The Watch might say it took longer to fall asleep than you would have estimated. That is what I initially thought. But I soon learned that the Smartwatch is incredibly good at detecting subtle movements. Now, even when the Smartwatch says it took me longer to fall asleep than it seemed, I am inclined to believe it.
- The Smartwatch might also say you fell asleep sooner than you would have estimated. The watch uses movement to determine when you fall asleep. If you lie in bed extremely still until you fall asleep, your Smartwatch might record that you were sleeping even though you were not. However, keep in mind that people with insomnia tend to underestimate how much time they sleep. It is quite possible that you were in fact sleeping even though it seemed as if you were just lying in bed awake. So, unless you are sure the Smartwatch is wrong, I suggest giving it the benefit of the doubt.
Bottom Line: There is a good chance that a Smartwatch can help determine your SOL with reasonable accuracy, and it is pretty easy to use for that purpose. Check out how well it does for you, based on your own sleep patterns.
- Mid-Sleep Awakenings — The Apple Watch measures every time you “wake up” during the sleep episode. It is extremely sensitive to movement, perhaps a bit too sensitive. Each night it records several “awakenings” that last for only one or two minutes. Am I really “awake? I do not recall being “awake.” Probably I am just tossing and turning a bit. Very brief awakenings, including short trips to the bathroom, can be ignored if you fall back to sleep within a few minutes. On the other hand, being awake for more than a few minutes should be recorded. For those instances, the Watch is especially useful because it tells you exactly how long you were awake. Based on my experience, this data is accurate. I trust it more than my memory. And it is so much easier to use the Smartwatch data than to try recalling and recording those awakenings the next morning.
Bottom Line: In my experience, the Smartwatch provides reasonably accurate data on the number and duration of mid-sleep awakenings. However, you need to see how accurate it is for you. There is a good chance you will find it helpful.
- Time of Final Awakening — The Smartwatch will report when you stop sleeping. It senses movement and uses that information to determine your wake-up time. If you get out of bed soon after you wake up, then that data can be relied upon. However, if after waking, you lie in bed for a while very still, the Smartwatch might “think” you fell back to sleep. Often the Watch will be correct, even though you might not believe it. If you are absolutely certain that you were awake, ignore the additional sleep time. Otherwise, give the Smartwatch the benefit of the doubt.
Bottom line: If you get out of bed shortly after waking, you can safely use the Smartwatch data to record your Time of Final Awakening. If you lie in bed without moving for a while after waking up, then you must decide whether the Smartwatch data is correct.
- Total Sleep Time (TST) — The Smartwatch calculates the total amount of time sleeping during the entire sleep episode. Based on my experience, the calculation seems correct. However, keep in mind that it will subtract all Mid-Sleep Awakenings, even those that last for only a minute or two. These short “awakenings” are often nothing more than rolling over in bed. Keep that in mind when you calculate TST.
Bottom Line: The Smartwatch calculates your TST, which is much easier than doing it yourself. Still, you will have to decide about those times when you are lying in bed motionless. If you are certain that you are not sleeping, then subtract those times from your TST.
5. Duration of the Sleep Episode (DSE) — The watch does not calculate DSE. However, DSE is easy to calculate on your own. Simply write down two things: a) The time you began trying to sleep (e.g., lights out); and b) the time you woke up and stopped trying to sleep. The amount of time in between is the DSE. For example, if “lights out” time was 11:00 PM and you stopped trying to sleep at 7:00 AM, your DSE would be 8 hours. Remember, your DSE is the same regardless of how long it took to fall asleep, or how long you were awake during the night.
6. Sleep-Efficiency — The Apple Watch does not calculate Sleep Efficiency. It will record the percent of time you were awake. But that number does not equal Sleep Efficiency. Rather, it simply refers to the percentage of time you were awake from the time you fell asleep until you woke up. Sleep Efficiency refers to the “percent of time you were awake” during the DSE (Item 5 above). To calculate Sleep Efficiency, you must use the formula in the book, which is TST (Item 4 above) divided by DSE (TST/DSE). That said, there is one sleep pattern when you can use the “percent of time awake” to calculate Sleep Efficiency. That pattern is when you fall asleep immediately after you start trying to sleep (lights out), AND you stop trying to sleep immediately after waking up. In that case, all you have to do is subtract the “percent of time awake” from 100 to get your Sleep Efficiency score.
Bottom Line: In most cases you will not be able to use the “percent of time you were awake” to calculate Sleep Efficiency. However, you can use the TST provided by the watch to help you calculate Sleep Efficiency, which is TST divided by DSE.
—————————————————————————————————————————–
Final comments:
- The information above represents my subjective impressions based on several months of using an Apple Watch Series 9.
- Research suggests that most Smartwatch models provide reasonably accurate sleep data. But none are perfectly accurate. Regardless of which Smartwatch you use, always compare the data from the Smartwatch to your own sleep record. If there is a good match, consider using the Smartwatch data to help monitor your sleep.
- Your SomniLog does not have to be perfectly accurate. Also, apart from Sleep Episode Rationing, none of the sleep log data is necessary to practice the other SomniSkills Workbook sleep techniques. So, do your best with the SomniLog. No matter what, keep practicing the techniques in the SomniSkills Workbook. Remember that the SomniSkills Workbook teaches the same techniques used in Cognitive Behavioral Therapy for Insomnia, a scientifically validated treatment for insomnia recommended by most health care providers.
—————————————————————————————————————————–
Footnotes:
- Some information from the SomniLog is required to practice Sleep Episode Rationing.
- New Research Evaluates Accuracy of Sleep Trackers (sleepfoundation.org) https://www.sleepfoundation.org/sleep-news/new-research-evaluates-accuracy-of-sleep-trackers#references-245484
- Accuracy of Three Commercial Wearable Devices for Sleep Tracking in Healthy Adults. https://pubmed.ncbi.nlm.nih.gov/39460013/