While the link between light and sleep is generally understood by the general public, we know much less about the impact of temperature.
To better understanding sleep, let’s first define something fundamental: the circadian rhythm. It’s a biological process that oscillates in a 24-hour cycle. It’s been observed in plants, animals and even cyanobacteria. Although circadian rhythms are endogenous (they're regulated from within), they are adjusted by external cues. As you might have guessed, two of the most important cues are light and temperature.
Our sleep cycle is closely related with two hormones: cortisol and melatonin. Cortisol plays an important role in our sleep cycle, waking us up and making us active. Our cortisol levels is highest during the morning and decrease during the day. On the opposite, melatonin is responsible for inducing sleep. Its level is the lowest during the morning and increase during the day, reaching its peak during the night, initiating and maintaining sleep.
Not coincidentally, our body temperature also varies during the day, following a similar pattern. It’s higher during the afternoon, when we are more active. It decreases in the evening to initiate sleep and reaches its lowest during sleep. Several medical studies already described the correlation. To fall asleep, we need to lose 1°C of core temperature. That’s why you may unconsciously flip your pillow when you have trouble going to sleep. During the night, our body stays cool. In the morning, the temperature has to increase to make us active and productive.
Our body needs different temperatures during the day, and each individual has a very particular temperature profile. What is perfect for one, might be too cold to another. There isn’t a one-size-fits-all best temperature for sleep. It would be too easy. This is the reason why passive cooling solutions, such as gel pillows, don't work for everyone.
To enhance sleep, we developed Moona. It’s a smart device that controls the temperature based on individual needs. It selects the optimal temperature for each stage of the night by understanding your sleep patterns. Our algorithms learn from your sleep history to better improve your sleep after each night.