30 December 2010 3 Comments

100 Days of Sleep – Part 4: Can I Plz Haz Deep Sleepz?

In yesterday’s post, I provided the two key elements for getting a good night’s sleep (for me, at least): 1) total amount of sleep, and 2) amount of deep sleep.

Getting enough total sleep is pretty straight forward to understand (if, perhaps, not always easy to achieve). But the data from yesterday showed I need about 60 minutes of deep sleep per night to feel totally refreshed the next day. The problem is, I only get about half that (as shown in the table in the first post of this series).

I decided to dig a little deeper (ha!) into my sleep data to see if there were any noticeable trends around deep sleep. I used the detailed sleep data that was included in the Zeo data export from the web to build the graph below. It shows the probability I’ll be in any particular sleep phase as a function of hours into sleep. In other words, when during the night am I in deep sleep?

The light gray color means there was no data available, e.g., I was already awake of the sensor wasn’t transmitting because I took it off.

The dark gray shows awake time. This shows, on average, it takes my about 10-30 minutes to fall asleep. This isn’t probably too accurate since I’ll often thumb through an RSS reader on my iPhone before deciding to actually go to sleep. The data also shows there is about a 5% probability at any point through the night that I’ll be in a wake state.

The light (ha!) green shows the probability I’ll be in light sleep. It’s obviously the bulk of my sleep.

The medium-green shows when I’m in REM phase. It’s interesting to see the strong peak about 3 hours into sleep, where there’s a 50% chance I’ll be in REM. It then levels off to about 30% for the rest of the night. But after 6.5 hours, the relative probability of REM increases. I believe this is typical.

Lastly, the dark green shows when deep sleep is most likely to occur. The largest peak is about an hour into sleep, where there is a 25% chance I’ll be in deep sleep phase. There is a second, smaller peak around 3.5 – 4.5 hours.

So, what now? I’m really not sure. I’ve looked around and haven’t found much of anything that suggests a way to increase deep phase sleep. I’ve already looked at a number of indicators associated with the Zeo sleep data I collected along with the sleep journal information, and I see absolutely nothing that suggests how I might get more deep sleep. I’ll probably figure out a way to collect more data going forward to help in maximizing deep sleep.

One possible solution would be a polyphasic sleep pattern. Since a large chunk of deep and REM sleep occur in the first 3.5 hours of sleep, would I do better to break my sleep up into two blocks of 3.5 hours? I’m not sure this is practical, but I might give it a try sometime.

So, that’s it for this round of sleep analysis. I’ll probably take another stab in 6 months or so. I have to put in a plug for the people over at Zeo. I appreciate how approachable and helpful they’ve been! Thanks!!

3 Responses to “100 Days of Sleep – Part 4: Can I Plz Haz Deep Sleepz?”

  1. Andi@Zeo 30 December 2010 at 4:08 pm #

    Hi Walter,

    First of all, great series. It’s been really fascinating to read about your sleep data exploration and you do a wonderful job of diving into the particulars.

    Secondly, in regards to Deep & REM sleep, it’s fairly normal in monophasic sleep to see more Deep within the first half of the night, while the second half gets more REM. It’s also normal for people to get less Deep Sleep as they age, whereas their REM and Light Sleep levels tend to stay the same. You might like this clip of our Science advisers, John Winkelman of Sleep HealthCenters in Brighton, discuss these changes. http://www.youtube.com/watch?v=o7kNaJEFIA4&feature=player_profilepage

    As far as increasing your Deep Sleep, things that we do during the day tend to have an impact on our sleep at night. Alcohol and caffeine consumption certainly reduce Deep and REM levels, while light or even moderate exercise can give us a boost. Everyone is different, so you might want to try tracking a few variables and see what happens.

    Looking forward to reading more!

  2. Sm 21 January 2011 at 1:27 pm #

    Could you run data on how much deep sleep you got in 6 hours and at which hour you went to bed? I don’t have references right now, but IIRC there are opposing circadian elipses of REM and DWS. It might be that at particular time (with regard to your inner clock) you get proportionally more DWS. These inner cycles tend to be close to length of solar day and get adjusted all the time, but still clock time is useful if they are not messed up.

  3. Omkar 20 May 2013 at 5:11 am #

    Got here from your post on Coursera, really fascinating stuff as I’ve also been reading into sleep patterns to optimise my productivity!

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