Sleep Series: Eating with the Sun

This is the third and final post from the Sleep Series. In case you missed it, Part 1 was on Sleep Basics, and Part 2 on Circadian Lighting. In this sleep finale, we’ll discuss ways to improve sleep...hint they don't come from nighttime routines. The sleep optimizations I've had the most success with over the years were daytime habits of diet and light exposure that came well before bedtime.

Circadian Diet

Intermittent Fasting (IF) is all the rage right now. It was the top searched diet trend on Google for the past two years. There are handfuls of studies showing intermittent fasting improves body composition and cholesterol levels. However, the jury is out on whether the health benefits of IF come from intermittency of eating in a defined window or whether it's that fasting has better synced our eating with our circadian rhythm. Regardless, I’ve adopted the “circadian diet”, eat when it’s light and fast when it’s dark.

I believe the future of IF is circadian-based. Our bodies evolved to be primed for food during the day so that we’d have plenty of energy for survival. The digestive process and action of insulin—a hormone that moves glucose from your blood into the majority of cells to be used as fuel—is at peak performance early in the day. Your resistance to insulin is highest at night, when you’re less active and your body thinks it should be slumbering. As a result, you wind up storing most of the calories you consume in the evening as fat.

I find many people on IF diets just use it as an excuse to skip breakfast. The word “breakfast” literally means to break the fast, breakfast is important and the health benefits of IF get lost on those who sleep late, skip breakfast, and eat until all hours of the night.

If you follow a circadian diet, you should have a 12 hour window for eating and fasting. If you want to stretch this window to 14 or 16 hours, it's best to start with a robust breakfast and taper off to a smaller lunch and light dinner, or no dinner at all.


As we discussed in the Circadian Lighting post, we’re spending too much time in low quality indoor light (100 lux). Our bodies have evolved to be in bright light during the day absorbing between 1,000-10,000 lux. Quality daytime light exposure will help keep our circadian rhythm synchronized. It also could have a protective effect against screen light exposure in the evening.

Evening Routine

I’ve adopted some night-time routines that I would recommend you doing if you haven’t already. At the very least, being aware of these habits should set you in the right direction.

Cold & Dark

This one's easy. Every sleep scientist seems to agree a cold and dark room are the ideal conditions for sleep. I set the temperature to 67 ºF and use blackout blinds. If you don’t have blackout blinds, I would try using a sleep mask like this one, which is less than $15 on Amazon.

We know our body temperature needs to drop by about 2 to 3 ºF to maintain deep sleep. The best thing you can do to lower your body temperature before bed is to take a hot shower. It seems counterintuitive but the heat makes your body work less to stay warm, and the end result is a lower core temperature. For the same reason, there’s been an influx of new “cooling” mattresses hit the market.

Drugs, Alcohol, & Supplements

Let’s start with the fun stuff. Unfortunately, THC and alcohol both block REM sleep. To minimize the impact these substances, the rule of thumb is, the earlier you consume, the better off you’re going to be. I’ve experimented with CBD and can tell you anecdotally the effects are minor – it’s the most over-hyped substance in health and wellness. Well, second to Trump’s suggestion injecting disinfectant cures Coronavirus. In all seriousness, the best sleep supplement “stack” is 3mg of melatonin and 200mg of magnesium bisglycinate. My doctor friends tell me the melatonin is placebo and they’re probably right. But I’m ok spending $20/month on this stack even if it’s for the placebo effect.

Blue Light

Exposure to blue and green wavelengths after dark can suppress the production of melatonin which makes you sleepy. My take; the negative effects from blue light screens is overstated. If you’re literally indoors all day and get no exposure to natural sunlight, it’s possible the 20-30 lux of blue light at night will effect your sleep. But if you’re outside for a few hours of the day the impact of blue light will be marginal. That said, if you’re working late, it doesn’t hurt to download f.lux for your laptop, and use Night Shift on your iPhone. One mistake I see friends make is buy blue light filtering lenses for their day-to-day optical glasses. Blue light is essential at the right time for biological functions so the last thing we want to do is decrease our exposure during the daytime. The better solution is to wear blue light blocking glasses (or fitovers) like these at night.

So here's the Hidden Lever: Eat with the sun; use your body's own natural cycle by consuming food between 7am and 7pm.

Until next time,