To feel and perform your best, you don’t just need enough sleep, you need enough quality sleep. We break down what you should avoid to sleep well and wake up refreshed.
Sleep is important. It allows your body to recover, but also to perform vital metabolic processes — such as the cleanup of toxic proteins in the brain, and of course, during REM sleep, your “sleeping” brain is very busy consolidating short-term memories into long-term memories.
Unsurprisingly, lack of sleep has been associated with a multitude of health issues. It has been shown to increase inflammationand impair focus, fat loss, insulin signalling, testosterone production, and cardiovascular health. More recently, it has also been associated with higher probability of inadequate hydration.
What can hurt sleep?
Let’s examine five factors that can impair it.
Light helps regulate the human biological clock, notably through melatonin, a hormone that signals your body that it’s time to sleep. Blue light — which is produced by the sun but also by the screens of TV sets, computers, and smartphones — disrupts your production of melatonin.
Yes, if it emits blue light, even the small screen of a smartphone can make it harder for you to fall asleep. A small randomized crossover trial examining the impact of smartphones with and without blue light found that, even though smartphones with blue light didn’t significantly affect serum melatonin levels, they still reduced sleepiness. So if you have to use electronics before bedtime, consider installing a program that gradually reduces blue light from the screen after sunset.
Finally, know that even when you’re already in the land of dreams, light can still impair the quality of your sleep. If you live in an area where light pollution is a concern, consider completing your dark therapy by installing blackout curtains or using a sleep mask.
As we’ve just seen, lights that don’t keep you awake can still impair the quality of your sleep. Similarly, sounds that don’t wake you up can still increase stress and impair the quality of your sleep.
Not all sounds will have the same impact, however. Sudden noises are more likely to disturb your sleep than constant noises. For instance, the noise of your running air conditioner might not bother you too much — it might even provide soothing white noise and mask more bothersome outside noise — but the same air conditioner may disturb you, or even wake you up, if it abruptly starts while you’re asleep.
The noises most likely to disturb your sleep are those that carry meaning. At equal volume, two people talking are more likely to wake you up than instrumental music, and you might be able to sleep through heavy traffic noise (though not without loss of sleep quality) yet awaken with a start if your baby makes a much softer but disquieting sound.
So if you must sleep in a noisy environment consider getting earplugs. Keep in mind, however, that earplugs attenuate high frequencies more than they do low frequencies— they may protect you against cars honking, but not much against traffic rumble. Fortunately, honks, being sudden noises, are more likely to wake you up than traffic rumble; but traffic rumble, if loud enough, can still impair the quality of your sleep.
So yes, as a rule, light and sound should both be minimized. Each has its use, however. A small, warm nightlight may reassure children and help them fall asleep (though it can also impair the quality of their sleep if left on overnight), and soothing music may help older adults with insomnia (though the volume should be kept low).
Elevated core body temperature has been associated with insomnia. Thus, if your bedroom is too warm — warm enough to raise your core body temperature — you may have trouble falling asleep and are likely to experience a decrease in the quality of your sleep.
Conversely, reductions in core body temperature have been associated with reductions in sleep latency. Thus, if your bedroom is cool — cool enough to lower your core body temperature, but not so chilly as to be uncomfortable — you may fall asleep faster and enter the deeper stages of sleep sooner.
Even if high temperatures don’t prevent you from falling asleep, you should still strive to sleep in a cool room, for heat can impair sleep quality more than noise does.
Alcohol is a depressant of the central nervous system; it causes relaxation by binding to GABA receptors in the brain. In other words, alcohol helps you unwind; and you may think it helps you sleep better. The research, however, shows otherwise.
Yes, at first, alcohol can help you fall asleep, but this effect fades off after a few days if you keep drinking close to bedtime. And right from the start, it will impair the quality of your sleep. Ironically, alcohol-use disorders have even been linked to insomnia, though their being cause or consequence is uncertain.
Caffeine is usually safe and it certainly has its benefits, but it also has some downsides .
Caffeine can block different adenosine receptors in the brain with varying effects. By blocking the A1 receptor, which promotes sleepiness when activated, caffeine can increase alertness. By blocking the A2A receptor, caffeine can increase dopamine levels, with stimulating and mood-enhancing effects.
The A1 receptor doesn’t seem to get desensitized, which may be why caffeine doesn’t lose its awakening effect. The A2A receptor does get desensitized, however, which is why coffee veterans don’t feel true stimulation even after drinking several cups — and why some people choose to cycle caffeine.
Because they no longer feel stimulated, coffee veterans often imagine that caffeine won’t affect their sleep. Indeed, many people can fall asleep with caffeine coursing their veins. Yet even as they slumber, caffeine makes them more alert and their sleep more shallow. For that reason, caffeine should be avoided within the six hours before bedtime.