Light and Sleep: Why More Light Means Less Sleep
Wonder why you can’t sleep under bright lights? Or why you feel restless when you scroll on your phone before bed? Light and sleep are closely linked, and understanding the relationship between them can help you to improve your sleeping environment
Light plays an important role in regulating the sleep-wake cycle
Humans used to depend on the natural cycle of sunlight and darkness for our circadian rhythm. But the round-the-clock presence of artificial lights has affected our sleeping patterns
Blue light (such as that emitted by electronic devices) affects sleep the most because it influences melatonin production and circadian rhythms
Did you know?
Until the Industrial Revolution, it was normal for people to sleep in two segments (or phases) per day. There was no reliable artificial light source at night then. So, people would sleep a couple of hours after dusk and wake up at night for 1-3 hours before falling back to sleep. This is called biphasic sleep
What’s the connection between light and sleep? Why do we sleep soundly in the dark but struggle to doze off when it’s bright? The answer has to do with the amount or kind of light we’re exposed to. Read on to find out how blue light affects sleep
Light and Sleep Have a Close Relationship
As it turns out, light is one of the most critical factors affecting sleep. Humans used to depend on the natural cycle of sunlight and darkness. But when technology made 24/7 illumination possible, it messed up our light environment, especially at night.
The innovation of artificial lights increased human productivity and economic growth. At the same time, it disrupted our internal biological rhythms, becoming a major source of modern sleep problems.
How Does Light Affect Sleep?
Light influences the circadian rhythm
You’re probably familiar with what we call the circadian rhythm or the internal body clock. Basically, your body follows an internal schedule that regulates many processes, including sleep.
A group of cells called the suprachiasmatic nucleus (SCN) controls the circadian rhythm. And the SCN is strongly influenced by light. When light enters the eye, it hits the surface of the light-sensitive retina, which tells the brain what “time” it is. Since sunlight is our major source of light, our circadian rhythm naturally synchronizes to it.
Light affects melatonin production
Melatonin, your sleep hormone, helps regulate your sleep-wake cycle. Its production is influenced by light exposure.
This hormone is produced in your pineal gland, a structure attached to the retina. If the retina continues to detect light at night, the circadian rhythm goes haywire. Instead of producing melatonin, the pineal gland suppresses it. Without melatonin, your body continues to feel alert, making restful shuteye elusive.
In contrast, when you’re in the dark, your melatonin production increases, making you feel drowsy. Cortisol, the hormone that activates the fight-or-flight response and regulates wakefulness also decreases, allowing your body to relax and prepare for sleep.
Do All Lights Have the Same Impact on Sleep?
The quick answer is no, not all lights have an equal effect on sleep. Of all the lights in the visible light spectrum, blue light affects your sleep the most. That’s because melanopsin, the photopigment that helps eye cells analyze brightness in the retina, is especially sensitive to shorter, cooler wavelengths like blue light.
Unfortunately, most common artificial light sources and electronic devices, including smartphones, televisions, tablets, and laptops, emit blue light. A 2014 study on the relationship between blue light and sleep showed that using an iPad emitting blue light inhibits melatonin production while reading a book does not. And increased exposure to screens has been linked to insomnia in teens.
Using the Link Between Light and Sleep to Snooze Better
Struggling with sleep is hard. But you can use the knowledge of light and sleep to help you catch more of thoseelusive zzzs. Here are a few tips:
- Decrease the amount of light in your bedroom. Use blackout curtains or rolling shutters to block the entry of unnecessary light.
- Switch to a low-power, warm color lamp in the afternoon to help your body wind down.
- When you're ready to sleep, turn off the lights and listen to a podcast or audiobook if you’re still not feeling tired. You could even put on our 'naplist,' a carefully curated playlist of soothing music.
- Reduce exposure to blue light in the evening. Dim your electronic gadgets 2-3 hours before bedtime. Aside from the disruptive blue light from screens, the constant notifications will also keep your alertness and stress levels high. You could exchange pre-sleep screen time for meditation to lower your stress levels and lull yourself to sleep.
- Use a weighted blanket. The added mass of a weighted blanket helps keep you grounded and relaxed, making it easier to fall – and stay – asleep.If you’re trying a weighted blanket for the first time, it’s worth learning more about what weighted blanket is right for you. Our Cotton Napper might be a good option if you’re looking for a soft, breathable style.
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