Sleep Hacking

Here's the things I've learned about sleep hacking.

• With insomnia, you're never really awake – fight club. Optimizing sleep is critical for a good life. If you're awake for an hour in the night, that's a lost hour, plus you're performance is poor during the next day. Improving sleep is probably one of the best ways of improving running performance and overall health.
• You can't control what you can't measure. A sleep tracker is worthwhile, though they need to be taken with some scepticism. They should give you a sense of your sleep quality and something objective to compare with your subjective feelings. I keep an eye on my Garmin sleep score, resting heart rate, and overnight HRV. I've not found waking HRV gives me anything useful, nor does overnight average heart rate as it's impacted too much by what I eat in the evening.
• You're not either asleep or awake; it's not a simple binary. This helped me understand the fuzziness of sleep, and how I don't remember all the time I'm "awake" and I might be aware when I'm "asleep". Realizing that looking at the time every hour doesn't mean I'm awake all the time, as there's no memory of the periods of sleep.
• Your eye has cells that are sensitive to violet/blue/green light for your circadian rhythm in addition to the cells that you use for vision. These "melanopic" cells are sensitive to light between 430-530nm, which is where your vision is less sensitive. So the brightness of artificial light for your vision will be different to how it impacts your sleep. There's a rough conversion table below based on the color temperature of the bulb, but most LED bulbs have a gap in their light output around the peak of the melanopic frequency.
• Dim light in the evening, 2-3 hours before bedtime in critical for sleep quality. The light should be below 10 melanopic lux. That's quite dim, even with a warm coloured bulb (2200 K).
• The dim evening light only works if you also get some bright light in the morning, as the dim light needs to be both absolutely dim and dim relative to the morning light. Bulbs with a colour temperature of 6500 K are pretty good if they're bright enough. It may also be important to have bright light late in the afternoon and early in the evening, such as 4-7pm for a 10pm bedtime.
• There are indications that some people may be more sensitive than others to light in the hours before bedtime, but that could also be dependent on their light exposure earlier in the day.
• The gap in LED frequencies makes evaluating artificial light tricky. For morning light, look for full spectrum and a source that shows the frequency curve, but that's hard to come by. You can simply go for very bright bulbs that are cold/daylight balanced but be aware they may have gaps in their frequency that makes them far less effective. Even SAD lamps are typically just bright lights, without any spectrum claims, and the gap in the brightness that coincides with the peak circadian frequency (480nm). https://optimizeyourbiology.comhas a database of SAD lamps and light bulbs, with independent verification of their light characteristics.
• The light level for sleeping needs to be below 1 lux, and ideally you shouldn't be able to tell the difference between eyes open and closed. Our bedroom has two Ikea smart blinds, one inset into the window with side channels, the other over the window space. It's still not good enough for bright summer light, but it's getting close.
• There's an emerging measure of light's impact on circadian rhythms. This is the Melanopic Lux, or Melanopic Ratio. You need at least 250 Melanopic Lux in the morning and less than 10 Melanopic Lux in the evening. See the table below and https://luminusdevices.zendesk.com/hc/en-us/articles/4409868024461-What-is-the-Melanopic-Ratio
• The iPhone night shift mode set to maximum should block most blue light. I have it set to full between 7am and 7pm daily, use dark mode, and keep the brightness just high enough to read the screen . https://www.displaymate.com/Spectra_69M.html
• I've found that using bright, cold balanced lights between 7am and 7pm, then dimmer, warm balanced lights between those times (when I'm awake) seems to help my sleep quality. Circadian rhythms like predictability!
• Getting fresh air into your bedroom is tough. Having a CO2 monitor that records the overnight CO2 is a starting point for understanding your situation. (I use Qingping air montiors.) We installed a blauberg Vento Heat Recovery Fan in our bedroom and another in the bathroom. They push/pull air from the outside while reducing the heat loss and dramatically improved our air quality and sleep quality. (You could have a window open, but the ventilation then depends on any wind and makes it hard to block out all light.)
• A consistent bedtime and rising time help reenforce the circadian rhythm, and sleeping later at the weekend is like continual jetlag.
• A cool bedroom helps the body cool off and improves sleep. I struggle with the bedroom temperature dropping in time for bed, and need to have the heating shut off in the bedroom some hours before bedtime. I hate getting into a cold bed, so I have a heated blanket that comes on before bedtime, and goes off when I go to sleep.
• Caffeine lasts a long time, so I avoid taking any after noon.
• There's some evidence that NSAIDs like Ibuprofen interfere with sleep, supressing melatonin production. https://www.sciencedirect.com/science/article/abs/pii/0031938495020365
• Most people wake up in the night to urinate once. As you'd expect I've found that heat training and dehydration both cause me to drink more later in the day, which then increases my need to urinate in the night.
• A short nap seems to help my sleep and recovery. This seems to be common with professional athletes who regularly nap. For me, the nap needs to be short (15-30 minutes) and early (11am-2pm).
• Protein before bed is a mixed bag for me. I think it improves my muscle recovery, but it interferes with my sleep. My heart rate in the first few hours is higher when I take protein before bed.
• Magnesium might help with sleep, and runners are even more likely to be deficient than sedentary people. I take 150% of the RDA as Magnesium Glycinate in a drink.
• Lavendar oil might improve sleep quality, and has been used for centuries. https://onlinelibrary.wiley.com/doi/abs/10.1002/ptr.7448
• After an ultradistance run, my sleep is messed up for that night. I accept that there's nothing I can do about that.

Approximate Melanopic Ratio

A crude conversion of a light bulb's lumins to the melanopic lumins can be made from the colour temperature.

Colour Temperature	Ratio
2400K (very warm)	0.40
2700K (warm)	0.44
3000K (warm/neutral)	0.53
3500K (neutral)	0.63
4000K (neutral)	0.67
5000K (cool)	0.84
6500K (cold)	0.98