'Can morning sunlight actually help me sleep better at night?'
If you struggle to sleep, there are a plethora of things you can do to help. From lavender sleep sprays, to special breathable bedding to (my personal favourite) bedtime stories narrated by Harry Styles. While all these products and changes have their merits, there’s one very simple routine-change that's been said to be the best way to improve your sleep - and it's surprisingly nothing to do with your evening.
Instead, it's about how you spend your morning - or, more specifically, where. Social media is full of people recommending getting outside in the sunlight early in the morning (or, as soon as you wake up) to help regulate your internal clock - also known as your ‘circadian rhythm.’
But as the term becomes more associated with bio-hacking and optimisation, of which I remain a sceptic, I wanted to know whether there's really any truth to morning light improving your night time sleep.
The circadian basics
‘Your circadian rhythm is essentially your body’s 24-hour clock, which is inbuilt in your genes, and it will keep ticking even in the absence of light,’ explains circadian biologist Aarti Jagannath, an associate professor at the University of Oxford. ‘But in order for that clock to have any relevance, so you know to do the right things at the right time of day, this clock receives information from light.’
This clock is in all cells in your body, but Jagannath explains there’s a master clock based in the hypothalamus in the brain. This master clock receives messages from the eyes, telling them how much light it’s seeing - therefore whether it’s morning, or evening. ‘The master clock then sends signals to the rest of the brain and body to coordinate all the clocks throughout the body,’ she explains. ‘This resets the whole system, so you know when to wake up, when to expect a meal, when to prime your digestive system, and when to start winding down.’
The problem, then, is that if you’re rolling out of bed directly into your car for your commute, or you head straight for your desk at home, you’re not getting enough light into your eyeballs, so your brain doesn’t receive those signals that it’s daytime. And if your clock is confused, this can have all sorts of knock-on effects on your body - you may feel tired all day and then struggle to nod off at night.
Just another bio-hack?
In recent years, the benefits of morning light have become associated with bio-hacking circles - generating the assumption that this is just another bro-science TikTok trend.
But the experts change my mind on this. Jagannath explains that, in our modern lives, our circadian rhythms really are constantly thrown out of whack. ‘Before electric lighting and artificial light, we only had sunlight we could rely on - and we spent more time outdoors,’ she says. ‘We’re spending more time indoors and less time in daylight.’ We’re also seeing more light at the wrong times - like just before bed. ‘Light at home in the evening is often no different to light in the office all day, so your clock gets really confused.’
The impact of light on sleep is backed up by multiple studies. Jagannath cites a study from the University of Colorado Boulder, which found that people who went camping (and were therefore exposed to only natural light) had better melatonin levels (which signals that it’s a person’s biological night) than those who stayed at home. Meanwhile, another study from 2014 found that night-time light was associated with poorer sleep quality and insomnia in older adults.
And sleep isn’t the only thing affected. ‘Mood is directly under control of the clock,’ says Jagannath. ‘We are naturally at our lowest in the middle of the night, so there is a daily cycle when mood is high and low.’ In fact, light is so well-known as a mood-enhancer that ‘daylight lamps’ are frequently prescribed for people who suffer from depression and Seasonal Affective Disorder (SAD). One study even found that morning sunlight directly reduced the length of hospitalization for patients with Bipolar Disorder.
Then there’s the impact on your metabolism. ‘There are many pathways in your liver that need to be switched on to metabolise your food, digest it properly, and ensure nutrients come out in the right way - and they’re also controlled by the clock,’ says Jagannath. If your body knows that it’s eating early in the day, it can process the calories and glucose much better than it would with those some calories and glucose levels in the evening.
Expert tips for morning sunlight
What’s the optimum time (and duration) to get out into morning light? Jagannath says there’s not enough research to give a definitive answer to this, but ‘we do know that the more outdoor light you get, the better the effect on the clock. As a ball-park, I’d say taking a 20-minute walk in the light as soon as you wake up is ideal.’
While you could definitely feel some benefits from sitting in your garden, Jagannath reckons combining movement with morning light will amplify the effects. ‘Exercise is another time cue to the clock, so if you have the two in conjunction, you get a much stronger signal.’
And, she says, you should notice the benefits quickly. ‘Waking up early, being active and being alert because you’ve seen that bright light means you’ll feel it the same day,’ she says. ‘They all compound one another so you’ll sleep better at night. Then if you maintain that, you’ll see it over the next few days as well.’
In the same way that morning light helps you wake up, dim light will also help you wind down. ‘Melatonin is also suppressed by light in the evenings, which pushes your sleep window further out and leaves you groggy when you wake up in the morning,’ says Jagannath.
The solution? Be mindful of your light sources in the evening. Switch off the main lights and use lamps after dinner, and be wary of spending too much time looking at screens too.
‘Some people think that switching your device to a night-mode where it turns your screen a reddish colour will prevent all the ill-effects, but sadly that’s not true,’ she says. Plus, it's not only the light that keeps you awake when scrolling at night, but the stimulating content too. ‘The content you’re engaging with, especially social media, will keep your mind you up,’ says Jagannath.
Working with the light
With this advice in mind, I try integrating morning light into my routine. I usually wake up and do living-room yoga before starting work, or I head straight to the coffee machine before settling at my desk. I decide I want to make my morning light walks more worthwhile, so I schedule a few early coffee meetings, book some gym classes, and plan to walk to some communal spaces during the day to work.
The first thing I notice, on day two, is how much more productive and motivated I feel. It’s hard to tell whether this is a direct result of the morning light, or all the other adaptations I’ve made to my routine - like getting out the house, getting my heart thumping first thing, and finding new spaces to work and feel inspired. Either way, it feels good - and Jagannath agrees that one morning habit can be a great way to incorporate a positive shift: ‘When you start taking one thing on board, it’s easier to start making improvements in other areas.’
Then there’s my sleep. I describe myself as a ‘bad sleeper’ - but I must admit I don’t do myself any favours. I tend to get ready for bed with the lights on, then I have a leisurely scroll through TikTok. Taking Jagannath’s advice, I dim the lights as early as possible (it feels cosier, if anything), put my phone on sleep mode and read a book instead. I track my sleep on my Apple Watch (which measures sleep using a heart-rate sensor and accelerometer, which detects motion), and the difference is huge. I’m falling asleep much quicker, and finding a better balance of REM sleep, core sleep and deep sleep - with less waking up, too.
During the first few days of my experiment, I’m lucky that it’s sunny every morning. But it gets harder towards the end of the week when I wake up to grey skies - and even, one day, a full-blown thunderstorm. Of course, the reality of getting all that light into your eyeballs - especially when you live in the UK - is not always possible. But Jagannath says any natural light, and any morning movement, is better than nothing - so I head out regardless.
Since my experiment, I’ve been maintaining the lessons I learned, because I really did notice a difference. Of course, it’s hard to say how much of that was down to the light itself. There are so many compounding variables, especially when it comes to sleep - like how much stress you’re under, or where you are in your menstrual cycle. I’ve also not been completely consistent every day. Late nights, especially on weekends, have made it hard - and there have been a few weekends where I’ve slept in obscenely late and almost missed daylight altogether. But Jagannath doesn’t discourage this either. ‘Your sleep is regulated by two factors: the clock, and sleep need. This says that the longer you’re awake, the more you need to sleep,’ she says. ‘So if you need sleep, it’s more important to get that rest whenever you can.’
Reassuringly, she says, ‘I wouldn’t sacrifice rest to maintain a routine.’ Still, if you can get yourself up and moving, I’d highly recommend starting your day in the sunlight.
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