Supplements that may lower anxiety at night and improve heart rate variability during sleep   I don't know enough about the HRV, the heart rate variability, to comment on improving that specifically. Heart rate variability is largely related to recovery from stress. So, I know the Oura ring tracks heart rate variability during sleep.    The main application that I'm familiar with HRV for is recovery from stress, especially from exercise. So anything that supports recovery — mainly is rest, is going to support that. Getting enough carbohydrates to support your high-intensity exercise is going to be another thing.   In general, nutrient density across the board is going to be supportive of recovery, and enough calories.    Now, lower anxiety at night before or during sleep I think is a whole different story.    You might have anxiety because you have not recovered well from your exercise.    Maybe your cortisol is running high.    But it could be for totally different reasons, and that's a giant can of worms that I don't think really can be unpacked in an umbrella answer. I think that's kind of something that needs to be very individualized because it requires 10, or 15, or 20 follow-up questions.   But some of the first things that I would think about would be what are you doing to psychologically wind down? The fact is that this is not all about nutrition. It's not all about light hygiene. It's also about psychology. So, is your anxiety at night driven by overthinking? If so, what are you overthinking about? You may need to start a psychological wind down routine if this is your issue.    And then, there are so many other potential causes of anxiety that you really have to address it on a case-by-case basis, but those are the top things that I think about.   This Q&A can also be found as part of a much longer episode, here: https://chrismasterjohnphd.com/podcast/2019/02/09/ask-anything-nutrition-feb-1-2019/   If you would like to be part of the next live Ask Me Anything About Nutrition, sign up for the CMJ Masterpass, which includes access to these live Zoom sessions, premium features on all my content, and hundreds of dollars of exclusive discounts. You can sign up with a 10% lifetime discount here: https://chrismasterjohnphd.com/q&a