Eating unhealthily, with few vegetables and foods with heavy fast carbohydrate (sugar/glucose) content, has been associated with bad sleep1. It’s therefore wise to actively manage one’s eating habits to ensure the best quality sleep. Here is some info about common diets and eating habits, and how they might affect one’s sleep and therefore one’s polyphasic abilities.
Low carbohydrate / Ketogenic diet
It was suggested by some people in the polyphasic sleeping Discord that a Ketogenic diet (low carbs, adequate protein, high fat) is helpful for polyphasic sleep because consuming carbs increases cyclical tiredness and/or overall sleep need. So far only anecdotal evidence supports this claim. Hypothetically, the ketones metabolism supposedly minimizes cell oxidation relative to glucose, which in turn leads to the body needing less time to repair itself. There is a lot of research done on the topic, but it seems like every individual research done yields varying results, for example some studies claim the Ketogenic diet increases the amount of SWS and reduces REM, while some others say it decreases the amount of SWS needed to recover. Further research in terms of directly affecting polyphasic sleeping is required in this area.
Eating only one meal a day has been anecdotally shown to cause no problems as long as it’s kept with enough distance to the next sleep session. Make sure to reinforce the circadian morning, either with a daylight lamp or with sunlight if breakfast is not eaten.
Avoid consuming too much sugar or other carbohydrates. After consumption of mainly sugar you get a boost in energy for up to 45 minutes, during which it’s going to be very hard to fall asleep. Abundant sugar mixed with plenty of fiber, protein, and/or fat should reduce the intensity of the sugar high but make it last up to a couple hours. When this wears off, you’ll reach an energy low for as long as a couple hours where you risk oversleeping.
The quality of your sleep will also suffer. SWS will be replaced by light sleep, sleep latency onset will increase, and you’ll be more prone to waking up in the middle of your sleep2. High-carbohydrate diets have however been associated with significantly shorter sleep latency3, but this might not matter as polyphasic sleep will decrease the sleep latency naturally.
A low protein intake (<16% of energy from protein) was associated with poor quality of sleep and marginally associated with difficulty initiating sleep, whereas a high protein intake (>19% of energy from protein) was associated with difficulty maintaining sleep4. But post-hoc test results showed that high-protein diets were associated with significantly fewer wake episodes than control diets3. This means that the results are inconclusive, and one can’t be sure how altering one’s protein consumption will treat their sleep structure and needs. Note that the second study only had about 1% the participants compared to study number one, so fewer wakes has weaker evidence. It’s still clear that many people do get their sleep altered in some fashion from changing their protein consumption.
Eating time versus sleep time
It is generally suggested that it is better to eat just after waking up from sleep so that your body isn’t having to digest food while sleeping, as this reduces the quality of the sleep5. Indeed it can be very hard to sleep if your belly is overflowing. Also avoid excessive hunger, particularly if your body is not used to this. Some training should automatically happen during adaptation as it’s important to keep a fast of at least 8 hours during the night, because nighttime eating has been directly linked with a messed up circadian rhythm and diseases like diabetes, cancer, and cardiovascular diseases. The safe bet is to avoid eating 2-3h before sleep, however some light snacks up to 250kcal (like a banana) should be okay to eat 1 hour prior to a sleep session.