What Is Sleep Latency, And Why Does It Matter?

Sleep latency, also known as sleep onset latency or SO, is making headlines—and for interesting reasons. A new study conducted in the UK (which has yet to be released) is saying it’s the most important sign of restful sleep.

Let’s back up first. What exactly issleep latency? Sleep latency is simply the number of minutes it takes for you to fall asleep. Sleep psychologist Professor Dorothy Bruck, who is also the chairwoman of the Sleep Health Foundation explains that sleep latency is measured from the moment you turn the lights out with the intention of falling asleep to the point you enter the non-rapid eye movement (NREM) stage of sleep.

See Also: Understanding Sleep Patterns.

While this new study is bringing to light a new idea for when we hit the lights—suggesting how fast you fall asleep is more important than how long you sleep—it’s still unavailable in its full text form, so we can’t speak to how scientists came up with this conclusion. Still, sleep experts have known how important sleep latency is, so we can provide information about sleep latency, along with tips to help you fall asleep consistently and comfortably each night.

Why is sleep latency important?

Sleep latency lays down a strong foundation for solid sleep. If you have good sleep latency, you’ll have a higher chance of moving through the natural stages of sleep, non-rapid eye movement sleep (NREM) and rapid eye movement (REM). REM is that juicy, deep form of sleep, but both are critical to sleeping well and feeling rested in the morning. 

For more, read about the importance of REM sleep.

You may be wondering: How long should my sleep latency be?Oddly enough, the faster you fall asleep isn’t necessarily correlated to better sleep. Instead, researchers are saying 15 minutes is a sleep sweet spot. Here’s why.

Falling asleep too fast, in say five or 10 minutes, can actually be a sign of sleep deprivation. Sleep expert Dr. Delwyn Bartlett from the Woolcock Institute of Medical Research in Sydney explains:

“Falling asleep quickly combined with snoring heavily can be a sign of undiagnosed sleep apnea. Depression can also be linked to falling asleep extremely quickly as it’s a good way to stop thinking about your problems.”

However, taking too long to fall asleep can be a sign of a racing mind or stress, or can lead to insomnia:

“Lying down at night can be the first time your mind gets to work through the day’s stress, but the arousal caused by this thinking then keeps you awake. If you then start to worry that you’re not yet asleep, dropping off becomes even less likely – and, after a few days or weeks of this, insomnia can take hold.

The ideal time from being awake to falling asleep is roughly 15-20 minutes. So if you’re lying in bed at night counting sheep, frustratingly wanting to fall asleep faster, here are some things that can help: 

  • Put the phone away. Science has shown time and time again that exposure to artificial light before bed can be seriously detrimental to sleep, causing not only sleep deprivation, but an increased risk in weight gain and certain cancers. Try to limit screen exposure 2-3 hours before bed.
  • Establish a bedtime routine. Create a nightly routine so your body is aware it’s time to hit the hay. This could a combination of reading, drinking tea, meditating, or writing in your journal. The key is staying consistent so your body recognizes the routine and has an easier time falling asleep.
  • Keep the room dark. In addition to artificial light, any other light that can creep in your room (moonlight, car lights, or even the sun if you’re working the night shift) can damage your sleep Consider investing in some blackout curtains or a handy sleep mask to keep your room as completely dark as possible.

Once this new sleep latency study is released, make sure to check back on Sleepopolis to hear our take on it! Until then, focus on that sweet 15-20 minute length of sleep latency for a healthier night’s rest.


Laura Schwecherl

Laura is a journalist with nearly a decade of experience reporting and covering topics in the health, fitness, and wellness space. She is also a marketing consultant, where she works with impact-oriented startups to build marketing and editorial strategies. Outside of work, you can find her reading Murakami novels, writing amateur poetry, or trail running in her hometown, Boulder, Colorado.

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