Should I Sleep With the Light On?

Whether it’s a habit from childhood, the result of forgetting to switch off the lights, or simply the glow of a TV in the background, sleeping with lights on is more common than you might think. Yet even a small amount of light can have a surprisingly big influence on sleep quality. Here, we look at whether keeping a light on at night is really a bright idea – and share alternatives for those who aren’t fans of the dark.

Light plays a key role in regulating our circadian rhythm – the internal clock that tells us when to feel sleepy or alert. During the day, natural light keeps us awake and energised, stimulating cortisol production in the morning. At night, however, artificial lighting and screens can confuse the brain, suppress melatonin (the sleep hormone), and delay sleep. Blue light from phones, tablets, and LED bulbs is the biggest culprit – it mimics daylight and keeps the brain stimulated long past bedtime.

For the best night’s rest, align with your body’s natural rhythm: soak up daylight early in the day, then ease into dimmer lighting in the evening while keeping screen time to a minimum.

Sleeping with the lights on – especially over long periods – can lead to unwanted side effects, including:

Melatonin, often called the “sleep hormone,” naturally rises after dark, helping us drift off. However, exposure to light at night, especially blue light from phones, tablets, or overhead bulbs, can disrupt this process. The result? Delayed sleep onset and a lighter, more restless night. Research from Harvard Medical School shows that even modest evening light exposure can lower melatonin levels, which in turn can affect heart rate, blood pressure, and overall sleep quality.

Sleeping with the lights on doesn’t just affect when you fall asleep but also how well you sleep. Artificial light at night can stop you from reaching the deeper stages of sleep, like REM and slow-wave sleep, both of which are important for memory, mood, and mental clarity. Over time, this can increase your risk of developing sleep disorders – another reason why switching the lights off matters.

When your body’s natural sleep–wake rhythm is thrown off, it can be linked to weight gain and a higher risk of chronic conditions like diabetes and heart disease. Research shows that irregular sleep patterns may contribute to metabolic issues such as insulin resistance, making it harder to keep a healthy weight. Too much light at night can lower melatonin, the hormone that supports your body’s overnight repair work. That’s why keeping your bedroom dark is one of the simplest ways to protect your sleep and your long-term health.

When your sleep is disturbed, your focus, energy, and productivity during the day can take a hit. Whether you’re working, studying, or just getting through your daily tasks, fatigue from poor sleep can leave you feeling sluggish. If light is keeping you from reaching deep, restorative rest, it could be quietly sapping your energy and motivation.

While sleeping in complete darkness is generally recommended for the best quality rest, there are a few situations where a bit of light can be helpful. For some, especially children or individuals who feel anxious in the dark, a soft night light can provide a sense of comfort and security that makes it easier to relax and drift off. In some health or mobility situations, such as for older adults or those who wake frequently at night, a dim light can help reduce the risk of trips or falls.

Read our article on how to help your child sleep better.

If you need some light to sleep, it’s all about choosing the right kind. Warm colours like red or amber are far less disruptive to your sleep cycle than blue or white light. Try dim night lights or motion-sensor LEDs to limit prolonged exposure, and place them low to the ground so they don’t shine directly into your eyes.

Sometimes, sleeping with the lights on can’t be avoided. Here’s how to reduce the impact of them:

• Choose warm-coloured LED bulbs
• Keep the brightness low
• Use a night light positioned away from your face
• Wear an eye mask
• Set a timer so the light switches off once you’ve fallen asleep
• Limit screen time in the evening
• Use blackout curtains to block outside light

Lighting needs can vary with age, but generally, it’s best for children to sleep in complete darkness to support healthy melatonin production and maintain their natural circadian rhythm. For little ones who feel anxious in the dark, a dim, warm-toned night light positioned away from the bed can offer comfort – just be sure to switch it off once they’ve fallen asleep. The same approach applies to infants: use soft, low lighting during nighttime feeds and avoid blue light entirely. During the day, exposing babies to natural light early on can help establish a strong sleep-wake cycle from the start.

While sleeping with the lights on is a habit many of us have, it’s clear that darkness really is key to getting the best quality rest. Light at night can disrupt your natural sleep rhythm, affect your mood, and even affect your long-term health. If you’re not a fan of total darkness, choosing warm, dim lighting and following our simple tips can help you find the right balance. However, ultimately, creating a calm, dark sleep environment is one of the easiest ways to support deeper, more restorative sleep and wake up feeling refreshed.