How Light Affects Sleep Quality

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As the technology around us increases, so does the artificial light we are exposed to. Nightlights, phones, and televisions are common culprits of excess light in the bedroom. In fact, 90% of Americans report using electronics and subsequent disruptions in their sleep schedule.

The rise of ambient light in the bedroom, especially from technology, can impact our natural sleep-wake cycles. Adjusting any nightlights, reducing the impact of outside light, and reducing exposure to blue light from your phone or television before bed may help you sleep better.

Is It Bad to Sleep with the Lights On?

Sleeping with the lights on is a relatively new concept. Before the rise of electricity in the late 19th century, people predominantly used candles or gas lamps after dark, and there were very few sources of light to disrupt sleep once they went to bed.

In our modern times, it’s much harder to sleep in complete darkness. Some people may intentionally leave a small light or tv on while they drift asleep. Others may live in urban areas with street lamps and illuminated signs preventing a dark room at night.

Studies have found that sleeping with the lights on can impact your overall health.  The extra light can disrupt your sleep cycle, leaving you feeling exhausted the next day. Sleeping with the light on may also lead to weight gain as observed in a study of over 43,000 women who slept with their television on during the night.

One study also found that having even low levels of light while you’re sleeping can cause eye strain.

The Relationship Between Light and Sleep Quality

Your circadian rhythm regulates your natural sleep and wake cycles in response to the presence or absence of light.

In the human eye there are receptors that, when exposed to light, send information to the circadian system informing it of the time of day and whether to suppress melatonin (if it’s bright outside) or increase melatonin (if it’s becoming dark).

Exposure to bright, natural light is associated with improved sleep quality, the ability to fall asleep earlier and sleep deeper. Try getting outside during the day, especially if you work indoors under artificial light, to help reap the benefits of natural light exposure.

Unfortunately, exposure to artificial light such as fluorescent bulbs, phones, computers, and televisions does not have the same positive sleep impacts as natural light.

Artificial light can suppress melatonin secretion and increase nighttime waking, resulting in overall poor sleep quality. Constant disruption of the circadian system can impact your overall health, increasing the risk for various diseases such as breast cancer and diabetes.

What Causes Light-Induced Sleep Disruption?

Technology, international travel, shift work, and daylight savings times are all ways that light exposure can impact your circadian rhythm.

  • Technology: Using technology before bed is a common way that people expose themselves to artificial light right before they try to go to sleep. One study found that people who read an electronic reader before bed were more likely to experience sleep delay, reduced melatonin secretion, and increased drowsiness the next day. Disruptions to sleep aren’t just limited to e-readers, as any type of electronic device exposure before bed will likely result in sleep disruptions.
  • Jet Lag: If you’re traveling over five or more timezones, then you’re likely going to experience jet lag. Jet lag results from your personal circadian clock being out of sync with the local day and time of the area you’re in. Try following the sleep and wake patterns of the locals to help your body adjust.
  • Shift work: Shift work often requires you to be awake during the time of day that you’d naturally be asleep. Since shift work usually takes place during the night, the exposure to artificial light is greater. Therefore, shift workers are more likely to experience impaired alertness and performance than those not on shift work.
  • Daylight Savings: Daylight savings time is the setting of clocks ahead one hour or later by one hour to account for the changes in the length of days. This process occurs twice a year during the fall and spring seasons. Sleep loss and fragmentation is present during both the “fall back” and “spring ahead” time changes and these sleep disruptions can last up to a week after the time change.

Can Certain Levels of Light Exposure Improve Sleep?

Some research suggests that a certain amount of bright light exposure can improve sleep for some people. One study found that for people with Parkinson's disease, exposure to bright light in the morning increased alertness, improved sleep, and allowed them to fall asleep faster

Older people may also benefit from daily bright light exposure. A study of older adults aged 70 to 93 showed that exposure to bright light for 90 minutes a day improved their sleep quality and regulated their body rhythms.

For those who have depression, exposure to bright light may help improve symptoms. Bright light exposure for 45 minutes over two to four weeks showed improvement in depressive symptoms and sleep issues in a group of adolescents.

Tips for Optimizing Your Bedroom for Sleep

There are a few things you can do to reduce ambient light in your room and optimize it for sleep.

  • Blackout Curtains: Invest in some high-quality room darkening curtains. These curtains are usually made of thicker fabric that blocks light, allowing you to fall asleep and stay asleep without environmental light waking you up.
  • Red emitting nightlights: If you or your kids need to sleep with some light, then try opting for a red-emitting nightlight. There is some evidence that red light exposure during the night does not negatively impact sleep.
  • Reducing technology use:  Try to keep technology out of the bedroom as much as possible, and try not to use technology for at least an hour before you go to bed. If you feel like you have to do something in bed to wind down, reading a book or magazine can keep you occupied.
  • Soft Light Bulbs: If you have bright LED light bulbs in your nightstand lamps, you can try switching them out for a softer, warmer, incandescent bulb. This is especially helpful if you want to read before bed but don’t want to be exposed to bright light right before sleep.
  • Sleeping Mask: If room darkening curtains are outside of your budget or if your partner needs a red night light to sleep, try opting for a sleeping mask. They are fairly inexpensive, comfortable, and can be found in most stores or online.

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