TL/DR: Here are some strategies that helped me improve my sleep. Some of these are a bit unusual, and some I haven't seen discussed anywhere else. Interesting findings include: the "shoulder temperature test", using earplugs to program your mind for sleep, my confusion about sleeping masks, and building a positive-pressure clean-air bedroom.

Introduction

This is meant as an anecdotal experience report and a discussion starter. I don’t intend to make an evidence-based case for the interventions presented here, nor will I do literature review. When I write something like “it is best to do X”, this is meant in a mostly anecdotal sense, i.e. “doing X seems to work for me”.

Evening Activities

In order to be able to sleep well, a switch needs to happen in my mind: Away from goal-directed focus and towards open, relaxed presence. Any work done within 2-3 hours of bedtime will severely affect this switch.

It’s not just work: There are also some non-work activities that hurt my sleep if performed 2-3h before bedtime. These include cleaning up, watching movies and sex. 

A readiness for sleep seems to be accompanied by a relaxation in the digestive system, and this can be deepened intentionally. My perfect pre-bedtime activity is reading a book while meditating on the feelings in my stomach and gut, and allowing any tension there to dissipate.

Visualizations

I’ve developed several visualizations to put my mind into sleep mode. I will go through one of them as I lay in bed, and usually fall asleep soon thereafter. One of them goes like this:

The Home in the Forest

"I’m standing on a hill in some kind of natural landscape, working on some unspecified task. A kind of flying boat comes  to pick me up. Before I can get in the boat I need to leave the work on the hillside and be willing to come back tomorrow. The boat takes me to a clearing in the forest where - in this visualization - my home is. After landing, there’s a cartoon character greeting me. His task is to take every one of my concerns and worries and open TODOs, and safely stow them. I hand him these items one by one as objects, and watch as he carefully stores them in a basement and locks the door."

Noise and Earplugs

I like it absolutely quiet. Any noises should be below hearing level.

Over the years I’ve tried many different earplugs, and I encourage you to do the same. The difference between average earplugs, and the ones with the best fit, can be quite immense.

I wear wax earplugs on the right side and foam on the left - simply because my two ear canals are shaped differently.

Tried getting custom fitted earplugs, but they were made from a rubber that got too hot in the ears, and they had very bad noise isolation (far worse than non-fitted plugs).

I use earplugs always, even when sleeping in totally quiet locations and even for naps. This creates an additional sleep stimuli: The body associates the presence of earplugs with sleep, reducing the time it takes to fall asleep

Screens

People frequently recommend f.lux for Desktop computers. It makes the screen more orange at night, but doesn't change the screen brightness.

What seems important is reducing the actual monitor brightness, and switching to dark mode at night. I wrote a software to adjust screens based on an ambient light sensor.

Some ebook readers (including Kindle) have a backlight that can be made very dark. This is ideal for reading before bedtime.

Ambient Light

It needs to be absolutely dark. Most LED indicator lights on devices are way too bright for the bedroom. Black gaffa tape or nail polish takes care of that.

In the morning, there should be some natural light leaking in, or you can use a sunrise simulation clock. Waking up in total darkness would be bad I believe.

How much light you need to wake up depends on previous experience, obviously. I have trained myself to sleep in very dark rooms, thus a very small amount of light leaking in is already enough to wake me up quite well.

Circadian Rhythm & Food

What you do throughout the day influences your circadian rhythm and thus the depth & timing of sleep. What helps me sleep better at night is:

• Getting bright light in the early parts of the day. Ideally, the actual sunrise.
• Working out early in the day (if I work out after 3pm it might lead to bad sleep).
• Dinner no later than 6pm.

The "Moment of Maximum Tiredness"

Lots has been written on sleep timing, so I won’t re-iterate the obvious. What follows is personal experience.

Every evening, there seems to be a “moment of maximum tiredness”, lasting 15-30 minutes. It's not always at the same time. When I go to bed at that time, I can fall asleep very quickly and sleep is great. Going to bed later means I take longer to fall asleep and sleep quality is worse.

Going to bed earlier means, most of the time, that I’m unable to fall asleep. Or even worse, I might fall into a kind of half-sleep for an hour, then get back up and completely awake for several hours

The “moment of maximum tiredness” can sometimes be quite pronounced. This is a good sign. If it’s not very noticable, it usually means that my circadian rhythm is not strong enough (see above). Or that I’m masking tiredness with stressful activities or computer use.

What to do when waking up early

Sometimes I would wake up just 1-2 hours early. It seems that in this case, one should just get up and start into the day… well, this doesn’t work for me. Going to work with 1-2h less sleep means, I will be unproductive and crash after a short time. It’s better to remain in bed, even if it takes an hour to fall back asleep and I then oversleep. My emotional health will be much better than if I had gotten up earlier.

My checklist for "waking up 1-2 hours early" is this:

• Stay in bed unless it's absolutely necessary to get up.
• Check warmth, add another blanket
• Do progressive muscle relaxation
• Put on a sleeping mask
• If you still can't sleep, read a book for 15min and try again.

Wakeup Timing, Sunrise Simulation, Light Alarms and Clocks

I have created a light alarm clock using smart home hardware and open source software (Node Red and Home Assistant). Upon pressing a physical button, lights will go dark, and a soft morning light will turn on 8 hours later. There are three buttons corresponding to 8, 9 and 10 hours of sleep. I’ll press one of the three depending on how tired I am.

The advantage compared to commercial light alarms is this: It doesn’t have any display and it cannot tell the time. On most days, when going to bed, I do not know what time it is. This feels very relaxing.

Some people use sunrise simulation (meaning, the light goes on gradually). I am not sure how important that is. I have programmed it into my system but currently don't use the feature.

Sometimes I’m quite tired and go to bed much earlier than usual. In that case it seems important to wake up at the normal time, not earlier.

The Problem with Sleeping Masks

Some people rely on sleeping masks if their room isn’t dark enough. This does not work for me: When using a sleeping mask I’d fall asleep quickly, but sleep quality is very bad - feeling terrible the next day. Still don’t know why that is and would appreciate any suggestions in the comments. I have tried many different brands of mask, with no difference.

Some hypothesis:

1. Waking up in darkness can cause tiredness during the day.
2. The presence of the mask is annoying and prevents full relaxation.
3. The mask makes it warmer overall, and temperature has a powerful influence on sleep depth.
4. Even when the mask fits well, it might move during the night letting some light leak in.
5. The mask might make it completely dark visually, but your conscious mind knows that there is actually light in the room - and then your subconscious is unwilling to go into deep sleep.

When travelling, I pack blackout curtains and put them over the windows - so the sleeping mask becomes unnecessary. If sleeping outdoors, I’ll use a special blackout tent (Quechua Fresh & Black).

There is only one situation where I will use a sleeping mask: If I wake up early and can’t fall back asleep, the mask really helps. It’s the warmth and comfort and feeling of safety. 

Temperature

I sleep best at 16-18°C (60-64°F). Using a thin blanket regardless of season, sometimes two.

There's one gotcha here: When trying to fall asleep, I don't have a reliable perception of coldness. I would just notice the body unable to relax. What works for me is the “shoulder test”: For side sleepers, the shoulder that faces up is a reliable indicator of temperature. I grab that shoulder with my hand, if it feels noticably cool, it means an extra blanket is needed. Not sure if that test can be done for other sleep positions.

In summer, my basement bedroom reaches 24°C (75°F), which is 7° (13°F) above the optimum. In these hot weeks, sleep quality is significantly worse than in winter. I tried a Chilisleep water-cooled mattress, and found it to be absolutely useless in this situation: Half of my body would feel as if emerged in a puddle of water, the other half would be even hotter than usual (because the device cools the bed but warms up the room air).

If bedroom temperature rises further (> 24°C or > 75°F), this causes very weird symptoms. Sometimes I just dont get tired in the evening. Sometimes I feel as if part of my brain is awake the entire night. It’s a very disconcerting feeling and can wreck the next day.

Not only is the temperature at sleep time important. It also seems important to avoid the body getting too cold during the evening. When I’m outside on cold evenings, I’ll feel hot throughout the night and sleep quite badly. Some kind of “temperature backlash”.

Mattress

I have never spent time optimizing this. If on the road and I find myself with a bed that’s too hard, I’ll take my inflatable camping mattress (Thermarest Camper SV) and put it on top.

Pillow and Bedsheet

A foam pillow seems better than a (synthetic) feather pillow because it’s more consistent. There are some that contain several layers of foam which you can remove for height adjustment.

I always use the same thin blanket regardless of season, and add a second one if cold. I take my own bedsheet and pillow for travelling. This helps greatly.

CO2 and Air Pollution

There is evidence that CO2 reduces sleeping quality. In a small room with closed windows, CO2 builds up rather quickly (in my bedroom for example, it reaches a level of 1400 ppm within a few hours, and then remains on that level throughout the night).

Based on my research on air purifiers, it appears that most people living in cities would benefit from these devices.

Using a circulating air purifier in the bedroom presents problems:

1. A HEPA filter removes almost all particles on their first pass through the machine, but with a standalone device you are just circulating air around, meaning it can take a while until you achieve significant reduction. My research indicates a standalone device removes more than half of pollution in the room, but the question is how powerful and loud the device needs to be  in order to achieve that.

2. If you open the window for lower CO2, you let pollution in.

The solution is making the bedroom positive pressure. Through a hole in my bedroom door, a low-noise fan sucks air through a HEPA filter and blows it into the room. This means CO2 levels remain low at all times (because the bedroom door is near the terrace door), particulate matter is basically zero (because the HEPA filter removes almost particles), and dirty air cannot leak in (at least in theory).

Supplements

Lavender oil in the air helps relax. Magnesium and L-Glycine seem to increase sleep depth and some studies point in the same direction.

I don't have enough experience with Melatonin.