Week 2: On Light Therapy

Introduction

I recently blogged about my first week or so on light therapy using a light box. There were some impressive improvements – the time I spent napping was cut by over 50% as were the number of naps I took.

This week provides some less optimistic, but still positive, and interesting data…

The Data

Date Hrs Naps Date Hrs Naps Date Hrs Naps
6/8 1.5 1 4/13 1.75 1 6/15 1.5 2
6/9 0 0 4/14 2.25 2 6/16 .5 1
6/10 .5 1 4/15 1 2 6/17 1.5 1
6/11 .75 1 4/16 1.5 2 6/18 .5 1
6/12 1 1 4/17 2.25 2 6/19 2.5 1
6/13 .5 1 4/18 3.5 3 6/20 3 1
Total: 4.25 5 Total: 12.25 12 Total: 9.5 7

You’ll note that the hours spent napping are double those of the previous week – but still 2.25 hrs. less than those in April. Additionally, the number of naps increased – but not as significantly as the hours spent napping – this remained closer to last week’s number of naps than April’s naps.

Observations & Hypotheses

Is there a pattern here? I’m not sure. A few things stick out in my daily time record:

Observation: On Tuesday, I experienced discontinuous sleep – awaking from 1:30 am till 3 am. One might have expected this to result in additional napping the next day – but it did not. This actually is in keeping with my subjective experience that since using light therapy the amount I sleep the prior night doesn’t seem as directly correlated with how tired I am the next day…it seems that even with less sleep I am oftentimes more energetic if I utilize the light therapy.

This image of Confused Felipe is provided courtesy of Felipelbazeta under a Creative Commons Attribution-Share Alike 3.0 Unported License.
This image of Confused Felipe is provided courtesy of Felipelbazeta under a Creative Commons Attribution-Share Alike 3.0 Unported License.

Hypothesis: Light therapy causes me to experience wakefulness which diminishes EDS in a manner that more than compensates for lack of sleep. It is not that I am not suffering the effects of sleep deprivation, but that the EDS which I usually experience has been offset by the light therapy – so my overall state of wakefulness remains at least constant, even better than a full night’s sleep without light therapy.

Observation:

  • On Monday night I went to bed at 11 pm, experienced discontinuous sleep and excessive daytime sleepiness on Tuesday.
  • On Tuesday night I went to bed at 11:40 pm and experienced continuous sleep.
  • On Wednesday night I went to bed at 11 pm and experienced continuous sleep, but awoke early on Thursday and was unable to do light therapy per usual due to schedule and experienced excessive daytime sleepiness.
  • On Thursday night I went to bed at 11:45 pm and experienced continuous sleep, but awoke early on Friday and was unable to do light therapy per usual due to schedule and experienced excessive daytime sleepiness.
  • On Friday night I went to bed at 11 pm and experienced discontinuous sleep and am now awake and utilizing light therapy.

This data in and of itself isn’t significant enough to really provide insights – until it is combined with additional subjective data – and then, the subjective data is due to significant interpretive bias on my part. But, based on the combination of the above and my subjective data I hypothesize:

Hypothesis:

  • When I go to bed before midnight I am significantly more likely to experience discontinuous sleep.
  • Days where I experience excessive daytime sleepiness coincide with days where my use of the light lamp where reduced in comparison to other days.

Conclusion

I’m going to review more of my time logs over a wider period of days to determine whether my subjective observation of a correlation between a pre-midnight bedtime and discontinuous sleep is objectively true.

I’ll collect another week of data and look for patterns of light box usage increases with decreases in excessive daytime sleepiness.

Postscript

Instead of writing a separate post, here is the analysis of my sleep and correlations with a pre-midnight bedtime over the last eighteen days:

Date Pre-Midnight Total Hr Continuous Total Nap Hr
6/3 N 8 Y 2
6/4 N 5.25 N 1.5
6/5 N 6.5 Y 2.25
6/6 Y 9.5 Y ?
6/7 Y 8.25 N ?
6/8 N 6.75 Y 1.5
6/9 N 9.25 Y 0
6/10 N 7.75 N .5
6/11 N 7.45 N .75
6/12 N 6 Y 1
6/13 N 8.5 Y .5
6/14 N 7 Y 1.25
6/15 N 7.25 Y 1.25
6/16 Y 8.25 Y .25
6/17 Y 8.5 N 1.5
6/18 Y 9.25 Y .5
6/19 Y 7.75 Y 2.5
6/20 Y 7 Y 3

I went to bed before midnight on 7 out of 18 nights (39%) and out of these nights 29% I had discontinuous sleep.   I slept for an average of 8.36 hrs. each of these nights and napped for an average of 1.55 hrs. during those days.

The remaining 11 nights (61%) I went to bed at or after midnight and out of these nights 27% I had discontinuous sleep. I slept for an average of 7.25 hrs. each of those nights and napped for an average of 1.14 hrs.

Postscript Analysis

Getting valuable data is extremely difficult when it comes to humans. The number of variables contributing is astounding. At face value, there is a slight difference in whether I sleep continuously based on a before/after midnight bedtime. There is a significant decrease in time spent sleeping at night as well as daytime sleeping when I go bed after midnight.

However, I mistrust this data. Several variables may throw it off:

  • For several of these days I was involved with John & Amy’s wedding. This involved significant travel, increased social activity, etc. This could have had a significant impact on my sleep/nap schedules.
  • I utilized light therapy throughout much of this time – and it seems to me that the amount of discontinuous sleep when I went to bed after midnight increased post light therapy…I suspect this is due to a reduced need for sleep.
  • I did significant IT consulting work since beginning light therapy – which can, at times, be quite stressful – and which may have affected my sleep/naps.

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