Sleep Through the Heat

How summer scent becomes an anchor for rest, mood and place

There is a certain kind of tired that only a heatwave produces. You go to bed exhausted and wake up more tired than when you lay down - top sheet kicked to the floor, the room too warm even with the window open, your mind looping rather than settling. If this has been your summer so far, you're not imagining it, and you're not alone in it.

What's less obvious is that the air in your bedroom - not just its temperature, but its scent - plays a real role in how well you sleep through a heatwave, and in how you feel when you surface from it. At FERN+FELL, we've always believed a candle is more than fragrance for fragrance's sake. It's a small, deliberate piece of a place, brought indoors. The research on scent, sleep, and our attachment to landscape backs this up more than you might expect.

Why hot nights wreck our sleep

Our bodies need to drop their core temperature to fall and stay asleep. Heat gets in the way of that. A 2025 study analysing 23 million nights of sleep, tracking data from over 214,000 people in China found that for every 10°C rise in ambient temperature, the odds of insufficient sleep rose by over 20%, with deep sleep affected most of all .

The European Insomnia Network noted that heat exposure during the night increases physiological stress - measurable in elevated heart rate and skin conductance - on top of simply making it harder to drift off. None of this is just discomfort. Poor sleep during heatwaves has been linked to the obvious lower next day mood but also reduced cognitive function.

So, if a heatwave is making your nights worse, your evening ritual matters more than usual, and this is exactly where scent earns its place.

The bedtime case for cedarwood and geranium

Cedarwood is one of the more quietly remarkable oils in our library, and it's the backbone of our REST | Cedarwood + Geranium blend. Its key active compound, cedrol, has been studied specifically for its effect on sleep physiology. A foundational 1998 study found that inhaling the scent of cedar shortened the time it took participants to enter non-REM sleep - a genuine sedative effect, not just a relaxing smell. A follow-up pharmacological study found that cedrol inhalation increased parasympathetic nervous system activity, the ‘rest and digest’ state the body needs to wind down, while reducing heart rate, blood pressure and respiratory rate.

Geranium works alongside cedarwood as an emotional stabiliser. It's well represented in the aromatherapy literature for easing tension and lifting low mood. In studies involving menopausal women, an eight-week course of geranium-based aromatherapy massage was associated with measurable improvements in mood and depression scores compared with massage alone, relevant for anyone whose summer nights are complicated further by hormonal heat sensitivity, hot flushes or night sweats, which is exactly why geranium also features heavily in our PAUSE blend, created by our founder Sharon for her own menopause experience.

Waking up brighter, not just falling asleep easier

Here's the detail that often gets missed in conversations about sleep and scent: it isn't only about getting to sleep -it's about surfacing well too. A 2023 randomised crossover trial gave university students either bergamot oil or a placebo spray to use before bed and again on waking. The bergamot group reported significant improvements not just in falling asleep, but specifically in ‘sleepiness on rising,’ ‘refreshing on rising,’ and overall sleep length, alongside reduced depression, anxiety and stress scores.

That's the rationale behind pairing an evening blend with a morning one: our RESTORE | Bergamot + Mandarin is designed for exactly that first hour of the day.

Citrus oils generally have strong form here. One study found that simply diffusing orange scents into a waiting room measurably reduced anxiety and improved mood in patients compared with an unscented control - which is a useful thing to remember next time a hot, restless night leaves you starting the day on the back foot.

Why scent works on us this way: the place beneath the fragrance

This is where it gets interesting, and where it connects back to something we think about constantly at FERN+FELL: the relationship between scent, memory, and the landscapes that shape us.

Smell is unique among our senses. It's the only one with a direct neural route into the amygdala, the brain's emotional processing centre, bypassing the more roundabout relay system that sight and sound take. This is why a scent can summon a feeling and the place that feeling belongs to, long before a single conscious thought arrives. Research from Brown University has shown, across a series of studies, that memories triggered by smell are reported as more emotional and provoke stronger physiological responses than the same memories triggered by a photograph or a sound recording. It's why the smell of pine can instantly transport you back to a specific woodland experience for example.

Environmental psychologists call our emotional bond to meaningful landscapes ‘place attachment,’ and it's not a soft concept, it's measurably linked to wellbeing. A study of over 2,000 people in Japan found that place attachment accounted for nearly a third of the entire positive effect that feeling connected to nature has on mental wellbeing. Other research has shown that thinking about a meaningful place activates the same regions of the brain involved in positive emotion and self-identity, suggesting that our attachment to place isn't just sentimental, it's neurologically real.

This is the principle behind every FERN+FELL candle. We don't start with a fragrance brief; we start with a place, a feeling and a memory. Whinlatter's wet bark and resin, the mineral sharpness of the Solway coast, the thin, clean air at the top of a fell - and we build the scent from there. When you light one, you're not just perfuming a room. You're giving yourself a sensory anchor: something that can pull your nervous system toward a place that, for you, means calm, or clarity, or rest - even when the actual landscape is hundreds of miles away, or simply inaccessible at 11pm in a heatwave.

There's a parallel in the science of forest bathing, or Shinrin Yoku. Researchers have found that walking in forest environments lowers cortisol by over 12% compared with an equivalent urban walk, with much of the effect attributed to phytoncides - the aromatic compounds, including pinene and cedrol, that trees release into the air . Our WOODLAND | Cedar, Eucalyptus, Black Spruce, Pine blend leans directly on this. Forest Bathing inspired this scent experience - it's the closest thing we can offer to that clearing-of-the-mind effect of a walk under trees, without leaving your bedroom.

A simple ritual for hot nights

If your sleep has been suffering this summer, here's a small, evidence-informed ritual worth trying:

• In the last hour before bed, light something grounding rather than energising. REST (Cedarwood + Geranium) is built for this - it's the one blend in our library designed specifically around the sedative, parasympathetic-calming research on cedrol.

• If hormonal heat sensitivity is part of your picture - hot flushes, night sweats, a racing mind at 2am then PAUSE brings geranium together with frankincense, bergamot and sage, oils more broadly associated with easing both anxiety and the emotional volatility that can come with hormonal change.

• On waking, start your morning with citrus - especially after a poor night, reach for RESTORE (Bergamot + Mandarin) rather than scrolling your phone.

• For a midsummer evening when the windows are open and the air is heavy, SUMMER (Geranium, Basil, Orange) - or a quiet hour with WOODLAND, gives you the sensory equivalent of an uplifting garden, or a walk under trees, without having to leave the sofa.

None of this replaces the basics of beating the heat - cooler bedding, ventilation, hydration, and recognising when extreme heat is a genuine health risk rather than just discomfort, especially for older adults, infants and anyone with chronic health conditions. But within that, scent is a small, real lever. It can't lower the thermometer, but it can lower you into your nervous system's rest state, and into a place that, even briefly, feels like somewhere you belong.

That's really the whole idea behind FERN+FELL. A candle isn't a finishing touch. It's a way of carrying a landscape with you and giving your senses somewhere steady to land - heatwave or not.

Sources referenced

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This article is intended for general wellbeing interest and is not a substitute for medical advice. If you have ongoing sleep problems, or are in a vulnerable group during extreme heat, please speak with a healthcare professional.