How Light Affects Your Sleep

Do you sleep with your smartphone right next to your bed? Perhaps you have a smart speaker that emits light, or you fall asleep with the TV on? Any one of these can be damaging your sleep.

Sleep and Ageing Guide

It’s common to sleep next to devices that emit light, with the curtains open or perhaps with the TV on. But is this preference having a negative impact on your sleep? Daylight and artificial light can impact your sleep in different ways, so we’re going to get to the bottom of it now.

Does Light Impact Sleep?

Yes, light impacts your sleep—it has good reason to. You have a circadian rhythm that responds to light.  It essentially means that your body knows when it’s light and when it’s dark, so you can sleep in darkness and stay awake all day. Consider it an internal clock.

Even when your eyes are closed, imagine your hypothalamus (a part of the brain) holding a pocket watch close, as it ticks away with only two hands: one pointing to day, the other to night.

The watch is powered by your retina. Light enters the eye and lets your brain know when it’s dark, dimming or dazzlingly bright. This works even with your eyes closed—close your eyes in front of a window, now cover them with your hands. You’ll notice a difference.


Daylight is the main light that impacts your sleep, and it’s the one that your circadian rhythm goes by. Have you noticed that it’s difficult to fall asleep in the long evenings of summer, and you wake up groggy on dark winter days?

This is down to that circadian rhythm pocket watch your hypothalamus holds. It adjusts based on what light is going on outside. It’ll slow as the days lengthen and speed up as they shorten, which is why you’ll find yourself getting sleepy in the dimmer evenings.

When the light dims, the watch gets closer to the “night” point on the clock. Your brain tells your body to start producing melatonin, the sleep chemical, and you start getting colder. This is meant to make you drowsy in preparation for sleep.

Once morning comes your brain knows it’s time to stop the excessive melatonin production and ensure you’re warm and alert. Cortisol jumps into action to help you feel more alert. Now you’re ready to face the day.

How Artificial Light Affects Your Sleep

As the watch adjusts to the light, can it adjust to other light sources too? These days artificial lights are everywhere—from the obvious, like ceiling lights, to the not-so-obvious on your phone.

Lights and Lamps

If you’re afraid of the dark, is it okay to sleep with the light on? Or can you keep it on full blast until right before you’re due to sleep?

Unfortunately, no. It’s best to have dim lights on before you go to sleep to help your circadian rhythm watch stay on track. Lights and lamps can confuse it, disrupting the rhythm, and you may find it difficult to fall asleep and wind up groggy in the morning.

Of course, sleeping with the light on occasionally won’t hurt you significantly, but it may impact you severely in the long run. Not only can it lead to sleep deprivation, but it can lead to some serious health risks! One study reveals that sleeping with the light on may lead to a higher chance of female breast cancer.


Electronics are dim, you can control screen brightness. Aren’t they safe, then? Sadly not.

Your disappointment is understandable. Surveys reveal that most Brits are almost always glued to a screen of some kind. Some even check it if they wake up at night. BBC News reports that most children sleep with a phone next to them, so it’s an issue at every age.

This is something to solve ASAP—the blue light from screens can harm sleep. Experts at Harvard Health go into it in detail here, but here are the basics: the circadian rhythm has a higher sensitivity to blue light held near the face, and it can delay melatonin release. So, your brain and body stay active and it’s harder to fall and stay asleep.

It’s best to keep phones, televisions and computers out of your bedroom. If you need to wake up in the morning, consider an alarm clock.


Now, nightlights. Nightlights have to be harmless. Your child is afraid to sleep without them, and there’s nothing you can do.

Yet again, night lights are another light source that can impact your sleep negatively. It’s still a dim light, so its negatives apply.

While it’s safe enough to have a dim light on before going to sleep, it’s best to turn it off before, or just after, a child falls asleep. It won’t do as much harm as blue light or fully bright light, but sleeping in total darkness is always best.

Optimizing Nightime Light for Kids

As we said, nightlights can be a necessity for kids. So, why not find a way around them? Here’s a suggested bedtime routine for kids to ensure they feel safe and secure with the lights on, and don’t notice when they turn off.

Before bed, limit exposure to bright lights. Take your child upstairs into their dimly lit bedroom with yellow or orange, warm lights by their bed. Here’s when your child can change into their night things, get their bed ready and choose a book to read before bed.

After brushing their teeth in a hopefully dimly lit bathroom, the child should get into bed and read to relax in the low light before sleep. Once it’s time to sleep, on goes the night light and off go the dim lamps—and here’s where you get clever.

Blinds and curtains closed, door closed, lamps and lights all off, consider letting a nightlight with a timer be the only light source in the room. The child will fall asleep to the night light, and the light will turn itself off so it’s not there to disrupt sleep quality or duration.

If your child wakes up during the night, consider placing a dim motion-activated light near the bed. That way if your child gets up, the light switches on and your child feels safe again.

Optimizing Your Room for Better Sleep

As for you, you need the same dedication you’re giving your child. Blinds and curtains—blackout curtains if needed—are a must to keep out city or street lights, car headlights and even the sun if you need to wake up late, but the sun rises early.

Keep electronics out of the bedroom, and consider a dimmer switch for your overhead light or invest in some dull lamps for your bedside tables.

Like your child, you should relax screen-free before bed to ensure you get the highest quality of sleep possible. Avoid turning lights on during the night if you can, and if you have to, try keeping them dim. Ideally, you want to avoid checking your phone when you wake up at night, too.

Optimization for Shift Workers

It’s a different story for shift workers, and there’s been a 5 per cent rise in night shift workers since 2013. As nightshift workers make up such a vast portion of the population, it’s important to know how to handle this lifestyle shift if you or a loved one end up in the situation.

If you work nights it can be incredibly difficult to keep daylight away. If you sleep all day, you may end up with no exposure to daylight at all. This can seriously throw off your circadian rhythm.

Invest in some blackout curtains that you close before you go to work, so you enter a dark environment as soon as you intend to sleep. Keep lights dim, and sleep the day away to your heart’s content.

Try to wake up when there’s at least a little bit of sunlight left in the day, as sunlight can boost your energy. But this is the UK after all and you’re likely to be hit with a cloudy sky and a dull outdoor space—so investing in a fluorescent lightbulb or lamp would be wise. You can get ready for work using this light to help wake yourself up and prepare your body for the night shift.

Try your best to artificially create a day/night cycle of lights and it can keep your circadian rhythm on track. Your rhythm will be on opposite times to non-shift worker’s, but it’s what’s necessary for your health, comfort and productivity at your job. Daylight exposure in slumber will negatively impact your sleep you may end up sleep-deprived, which hurts cognitive function.

Sleep Apnea Risks

When you have sleep apnea you’re more at risk for cardiovascular disease as well as stroke. As you’re not breathing your vital organs are missing out on the oxygen they need to function, damaging them in the process.

Sleep apnea is one of the most dangerous conditions there is thanks to these risks, and thanks to the symptoms. If you stop breathing for too long in sleep you’re at risk for brain damage, or even death.

If you fear you have sleep apnea, we urge you to consider it an emergency and seek help as soon as you can. Sleep apnea can easily play a role in a multi-faceted death and often goes untreated.

Final Thoughts

Keep that internal pocketwatch on track, ensure you’re staying away from bright lights before and during sleep, and you should see significant improvements in the quality of your sleep in the long run.

Disclaimer – The advice above should not be considered medical advice and is meant to provide an overview of the kind of sleep issues seniors and older people may face. If you are at all concerned about your health, no matter what age, always consult your GP.