Poor sleep is one of the strongest predictors of low mood and anxiety. Understanding that cycle, and knowing how to interrupt it, is one of the most practical things you can do for your wellbeing.
What You Eat Is Talking to Your Brain
Around 90% of your serotonin is produced in the gut. Feed your gut poorly, and you may well feel the effects on mood, anxiety and sleep quality.
Here are the key nutrients you need to know:
- Tryptophan (found in turkey, eggs, oats and seeds) is the foundation to serotonin and melatonin, your sleep-regulating hormone. Chronically low intake affects both mood and sleep onset.
- Magnesium (leafy greens, nuts, dark chocolate) supports nervous system regulation and helps the body transition into sleep. It’s one of the most common deficiencies I see, and one of the most overlooked.
- Omega-3 fatty acids (oily fish, walnuts, flaxseed) are anti-inflammatory and have solid evidence behind them for supporting mood, particularly in depression and anxiety.
- B vitamins especially B6, B9 and B12 are essential for neurotransmitter production. Low B12 is associated with fatigue, brain fog and low mood, and is extremely common in people on long-term medications like metformin or the contraceptive pill.
- Two kiwi fruit in the evening is a small habit worth knowing about. Research suggests kiwi eaten before bed can support melatonin production and improve sleep onset and quality
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Small Changes Can Make a Big Difference
Overhauling your diet or following a rigid sleep protocol is a big ask. What I see working in practice is far more achievable:
- Eat breakfast with protein eggs, Greek yoghurt, smoked salmon on rye, ideally within an hour of waking. This anchors your blood sugar and supports a healthy cortisol curve from the start of the day.
- Stop caffeine at midday. Caffeine has a half-life of around six hours. That 3pm coffee is still active in your system at 9pm, reducing sleep quality even if you do drop off.
- Create a wind-down buffer of 30 to 60 minutes before bed with dim lighting, no screens and something calming. Give your nervous system permission to wind down.
- Prioritise consistency over duration. Waking at the same time every day, weekends included, is one of the single most effective things you can do for sleep quality and mood stability.
- Notice the stress-eating pattern. Reaching for sugar or ultra-processed food under pressure is a very normal cortisol response. Acknowledging it without judgment and keeping more nourishing options easily accessible is far more sustainable than willpower alone.
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Supporting Your Circadian Rhythm, Starting Where You Are
One of the things I focus on with patients who are low in mood is the circadian rhythm. That’s the body’s internal clock that determines when cortisol rises, when melatonin builds and when sleep becomes possible. When someone’s really struggling, even getting out of bed can feel impossible, and that delay between waking up and being able to get up is often a sign that cortisol is low and slow to respond.
I start small. The first ask is to open the curtains. Natural light reaching the eyes, even from inside the room, tells the brain that it’s daytime. From there, I encourage sitting near a window for around 15 minutes in the morning. Then, gradually, get outside for a short walk first thing when that feels manageable.
This matters because daylight exposure, particularly in the morning and periodically through the day, tells your body what time it is. That anchors your cortisol peak where it should be, earlier in the day, so that as the day progresses, cortisol naturally starts to come down and melatonin can begin to build in the evening.
The result is a more reliable sleep signal at night. It’s one of the most powerful tools available for regulating mood, energy and sleep, and it costs nothing. The key is building it incrementally rather than treating it as another thing to fail at.
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Daily Habits Worth Borrowing from the World’s Healthiest Communities
The longest-lived, healthiest communities in the world, the so-called ‘Blue Zones’, share several things worth paying attention to. For mental well-being, try these:
- Movement Try walking to work, if possible, strength training, taking stairs instead of the lift, gardening, moving between meetings. Regular moderate activity helps stabilise blood sugar, reducing energy crashes and irritability that feed anxiety and low mood.
- Mediterranean-style eating Supports the gut microbiome involved in mood-regulating hormones. Steady, minimally processed carbohydrates, healthy fats, colourful plants, olive oil and oily fish are the foundation rather than expensive superfoods.
- Protected connection time A lifestyle ‘must’. Chronic stress worsens sleep, drives cravings and pushes people towards coping habits that can undermine everything else. A weekly shared meal, a regular walking friend, and hobbies, all reduce stress hormones and make every other healthy habit easier to sustain.
What you eat, the quality of your sleep, and the rhythm of your day are the foundations on which your mental well-being is built.
Richa Puri is an independent prescribing pharmacist and registered nutritional therapist registered with the General Pharmaceutical Council and BANT. www.richapurihormones.com
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