Temperature and sleep: what science really says
Before we can fall asleep, our core body temperature has to drop - by around 1 to 1.5 degrees Celsius. This is no small matter, it's biology. Our body has had this mechanism in it since the Stone Age: as the temperature drops, the brain signals that it is time to sleep. The sleep hormone melatonin begins to flow, the pulse slows down and the body goes into regeneration mode.
Prof. Dr. Matthew Walker, neuroscientist at the University of California, Berkeley, and one of the world's leading sleep researchers, describes it like this: A drop in core temperature of around 1-2°C is a mandatory prerequisite for good sleep. Bedrooms that are too warm interrupt this process - with measurable consequences for deep sleep and REM phases.
Andrew Huberman, a neuroscientist at Stanford University, adds: "If you specifically cool down your body, you can accelerate the onset of sleep by up to 25 % and extend the deep sleep phase by up to 40 minutes. This is the power of thermoregulation.
The optimum sleeping temperature: between 16 and 18°C
The National Sleep Foundation (USA) recommends a bedroom temperature of between 15.5 and 19.4°C. The Federal Environment Agency speaks of 17°C as the ideal value. Huberman and Walker cite around 18°C as the optimum value for most adults.
The problem: most German bedrooms are 20°C and warmer in winter - especially in modern low-energy houses. The result is shallower sleep phases, more frequent waking and less regeneration.
The optimum sleeping temperature according to research: at least 16-18°C.
Most German bedrooms are too warm - and thus rob us of valuable deep sleep phases.
»Many bedrooms are far too warm« - Dr. Annette Krop-Benesch
Chronobiologist Dr. Annette Krop-Benesch, an expert on the human internal clock, puts it in a nutshell:
„Many bedrooms are far too warm, especially in low-energy houses, which are not at all good for our sleep. A clear temperature difference between day and night is very important for our internal clock.”
- Dr. Annette Krop-Benesch, Chronobiologist
Krop-Benesch explains: "Our internal clock has hardly changed since the Stone Age. Back then, our ancestors slept outside - with natural temperature fluctuations between day and night. It is precisely these fluctuations that bring our sleep hormone melatonin into the right rhythm.
You can find the full interview with Dr. Krop-Benesch here on our blog →
Sleeping outside: the natural drop in temperature is the key
What happens when you sleep outside? The temperature drops automatically after sunset - exactly when your body needs it. You experience the natural day-night rhythm that your body has been following for thousands of years.
Prof. Kenneth Wright from the University of Colorado Boulder has shown in several studies what a single weekend of camping can do:
- Melatonin increase 1.4 hours earlier: You get tired earlier in the evening and sleep more deeply.
- Inner clock synchronizes completely: After a week in nature, the clock returns to its natural rhythm - for early risers and night owls alike.
- More sleep: In Wright's winter study, the participants slept almost 10 hours while camping instead of the usual 7.5 hours.
The reason: outside you are exposed to a light intensity of over 10,000 lux during the day - in a typical office it is often less than 500 lux. Your body receives a strong signal: „It's daytime.” When the sun goes down and the temperature drops, the second signal follows: „Now it's night. Sleep!” Melatonin production starts earlier and more strongly.
Good sleep is good health - according to research
What happens during sleep at night is impressive. Researchers at the University of Tübingen were able to show that T cells - the guardians of our immune system - become more active during sleep and are better able to dock onto pathogens. Just three hours of sleep deprivation is enough to measurably impair this function.
Dr. Krop-Benesch summarizes the work our body does at night: Melatonin ensures the storage of experiences in the brain, the healing of wounds, the activity of the immune system and the regeneration of our tissues - in other words, cell division. This all happens during sleep; during the day, the body is busy with other tasks.
Those who sleep less well - because their bedroom is too warm, because artificial light disrupts the release of melatonin or because the day-night rhythm is out of sync - deprive themselves of all these regeneration processes. Poor sleep also increases cortisol levels, the stress hormone, which in turn weakens the immune system.
Sleeping outside as a natural therapy
Dr. Krop-Benesch even sees medical potential: „Above all, it can help to restore the natural sleep rhythm, because sleeping outside allows you to breathe in fresh air without limits, feel the natural temperature difference between day and night and experience the dawn and dusk. I can imagine that people with sleep disorders, burn-out patients and people in old people's homes would benefit from this.”
Three factors come together when sleeping outdoors that are often missing indoors:
🌡️ Natural temperature
The evening brings the cooling that your body needs to fall asleep. No overheated air, no congestion under the comforter - just nature taking over.
🌿 Fresh air
The air quality outside is generally much better than indoors. Fresh air supplies the body with oxygen - and your lungs will thank you for it in the morning.
🌑 True light-dark rhythm
Without screens, without streetlights: outside, the inner clock experiences real darkness - the very darkness that really gets the melatonin secretion going.
The SkyHeia outdoor bed: sleep comfortably outdoors
That all sounds good - but who wants to lie on the ground when sleeping outside? The SkyHeia outdoor bed combines the best of both worlds: the natural comfort of sleeping outside with the convenience of a real bed.
On the SkyHeia you experience exactly what sleep research recommends: the natural drop in temperature in the evening, fresh air without limits, real darkness and the sunrise that wakes you gently and at the right time. Your body finds its way back to the rhythm it was made for.
Conclusion: The optimum sleeping temperature - outside is naturally available
Poor sleep is not destiny. Often it is simply the wrong environment: too warm, too bright, too little rhythm. What sleep researchers such as Matthew Walker, Andrew Huberman and Kenneth Wright measure in their laboratories is confirmed by chronobiologist Annette Krop-Benesch from her practice: our body loves nature - and sleeps better outdoors.
The optimum sleeping temperature is not in a thermostat-controlled bedroom. It lies outside, where nature and night work together to give you the sleep you deserve.
Are you ready to revolutionize your sleep? The SkyHeia outdoor bed shows you how good sleeping outdoors really can be.
Frequently asked questions about the optimum sleeping temperature
What is the optimum sleeping temperature?
According to research, the optimum sleeping temperature in the bedroom is between 16 and 18°C (approx. 60-67°F). The National Sleep Foundation recommends 15.5-19.4°C. Prof. Matthew Walker and Andrew Huberman cite around 18°C as the ideal value for most adults.
Why do you sleep better outside?
Three factors work together outdoors that are often missing indoors: the natural drop in temperature after sunset, fresh air and a real light-dark rhythm without artificial light. Studies by the University of Colorado show that even a weekend outdoors shifts melatonin production forward by 1.4 hours and significantly improves sleep.
What sleeping temperature does Dr. Matthew Walker recommend?
Prof. Dr. Matthew Walker, sleep researcher at UC Berkeley, recommends a bedroom temperature of around 18°C (67°F). He explains that the body needs to lower its core temperature by around 1-2°C in order to fall asleep - rooms that are too warm prevent this process.
What does body temperature have to do with sleep?
The body's core temperature is closely linked to the circadian rhythm (internal clock). It naturally drops in the evening - this is the signal for the body to release melatonin and switch to sleep mode. If the ambient temperature is too high, this process is disturbed, which makes it harder to fall asleep and leads to less deep sleep.
Is sleeping outside healthy?
Chronobiologist Dr. Annette Krop-Benesch confirms this: Sleeping outside helps to restore the natural sleep rhythm. Fresh air, natural temperature fluctuations and a real light-dark rhythm work together to improve melatonin production, the immune system and regeneration. People with sleep disorders or burnout in particular can benefit from this.
Sources:
- Walker, M. (2017). Why We Sleep. Scribner. | Center for Human Sleep Science, UC Berkeley
- Wright, K. P. et al. (2013). Entrainment of the Human Circadian Clock to the Natural Light-Dark Cycle. Current Biology. | CU Boulder (2013): A week of camping synchronizes the internal clock
- Wright, K. P. et al. (2017). Circadian Entrainment to the Natural Light-Dark Cycle Across Seasons and the Weekend. Current Biology. | CU Boulder (2017): A weekend of camping helps you fall asleep
- Huberman, A. & Walker, M. Guest Series on Sleep. Huberman Lab Podcast. | Huberman Lab: Protocols to Improve Your Sleep
- University of Tübingen (2019): How sleep strengthens the immune system. | Press release University Hospital Tübingen
- National Sleep Foundation: The Best Temperature for Sleep. | sleepfoundation.org
- Krop-Benesch, A. Interview with SkyHeia on the topic of outdoor sleeping and health (2022). | To the interview on skyheia.com →
