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Sleep hygiene is the upkeep of behaviors that influence the way you sleep. One common misconception is that these behaviors must relate directly to sleep itself. But many of them take place during the day and don’t involve literal snoozing—they’re included under the umbrella of sleep hygiene because they still have an effect on sleep.

The defines sleep hygiene as “a collection of behaviors distributed throughout the day that are not immediately sleep related but have sleep consequences.” likewise says that sleep hygiene consists of overlapping environmental, lifestyle, and habitual factors that “may interfere with or promote better sleep.”

If these definitions sound broad, that’s because they are! Your sleep is sensitive to so much of what you do. As you’ll see later on, everything from the temperature of your bedroom to what you’ve eaten and drank during the day can be a part of sleep hygiene.

A big takeaway here is that almost everyone can stand to improve their sleep hygiene. A troubling identify as sleep-deprived, and even if you think that you’re getting enough z’s, research indicates that .

Often, sleep-deprived people —they acclimate to the effects of the deprivation and think that they’re doing just fine at work and elsewhere. This tendency makes chronic sleep loss a cycle that’s tough to see, let alone break.

Even if you can survive on 6-or-so hours of shut-eye, you should know that the overwhelming majority of adults require to function at their best. Exceptions exist, of course, but they’re incredibly rare.

You’re more likely to be struck by lightning than you are to possess the gene that allows you to sleep 6 hours a night with minimum ill effects. As Dr. Thomas Roth says in Matthew Walker’s book, , “The number of people who can survive on 5 hours of sleep or less without any impairment, expressed as a percent of the population, and rounded to a whole number, is zero.”

Sleep hygiene isn’t all about sleep duration, either—the timing of your sleep matters too. Our world is structured in defiance of . Our jobs, studies, and social lives disrupt these biological rhythms, creating a misalignment between our ideal schedules for peak performance and how we actually plan our time. This disconnect can explain why when their class schedules don’t match up with their inner clocks.

Getting to know your circadian rhythm is thus an integral but often overlooked part of sleep hygiene—and one we’ll revisit in more detail soon.

You can! Better sleep hygiene is definitely achievable, especially when you’re educating yourself on sleep science and your own biological patterns. And when you start hewing closer to what your body needs from you in terms of natural sleep and scheduling, your brain automatically joins the cause. In fact, You just need to get out of its way!

A quick note—when we say “natural sleep,” we mean the kind of sleep your brain wants you to have: deep, reinvigorating sleep characterized by , and unimpeded by artificial disruptions, such as electric light or sleep aids. It’s much more difficult to reach this stage of sleep if your sleep hygiene is off.

If you’re worried that genetics may condemn you to chronic sleeplessness, take heart: . No matter your background, you’re primed to examine and revamp your sleep hygiene, and your brain is ready to help.

Sleep debt, simply defined, is the amount of sleep that you owe your body over the past 14 days or so. It’s a running total of the hours of sleep you’ve missed, relative to your sleep need. To better explain how it appears and builds, it’s helpful to look at a debt-free cycle of sleeping and waking.

If you were getting the perfect amount of sleep every night, you wouldn’t have any excess sleep debt. But, you’d still be experiencing a benign buildup of sleep pressure throughout your day, until its peak at bedtime. The sleep-wake cycle relies on sleep pressure to operate normally—if you never got tired at night, you wouldn’t sleep!

If you’re wondering why you get tired at all, you can blame adenosine. Scientists have correlated sleep pressure with this organic compound, which accumulates in your brain every minute you’re awake. As its concentration rises, leading to drowsiness. But when you sleep, the brain purges itself of adenosine, effectively resetting the pressure balance at 0 for the next day.

In the two-process model of sleep regulation, this daily buildup and nighttime depletion of sleep pressure is a process called sleep homeostasis. A homeostatic process is all about balance—a return to a desired stasis. The model says that this regulatory system exists in each of us, and pushes us toward the ideal amount and depth of sleep.

Think of the sleep homeostat like a seesaw in your brain that wants to be level. As sleep pressure and adenosine build on one end and the balance becomes upset, eventually the seesaw tries to even itself out. This homeostatic process has . Rats and mice, for example, both tend to sleep for a notably extended period of time following a bout of sleep deprivation.

Whether you’re a person or a rodent, if you’re sleep-deprived, you aren’t getting that full adenosine purge. Instead, you , compounding the negative effects of sleep loss until you can make an effort to rebalance the seesaw. When you’re saddled with this adenosine and all of its consequences, you’re accruing sleep debt, rather than responding to normal and healthy sleep pressure.

The repercussions of sleep debt are incredibly alarming. For example, after 10 consecutive nights of getting seven hours of sleep—one hour less than the recommended eight—.

If that doesn’t sound too bad, consider that 18 hours without sleep results in . A full 24 hours without sleep puts you in the position of someone with a BAC of 0.10%—higher than the legal limit in every state.

Furthermore, if you’re someone who drives often, your odds of crashing your car shoot up alongside your sleep debt. The that up to ⅕ of all fatal crashes involve a sleep-deprived driver.

Drivers who have slept for less than seven hours the night before dramatically increase their odds of crashing. Compared to those who slept at least seven hours, those who slept for 5–6 hours were about twice as likely to crash, whereas those who slept for four hours or less were 11 times more likely!

Thankfully, sleep debt is actionable—you can make it up, and doing so reverses the impairments caused by sleep deprivation. , participants who had only been sleeping 4.5 hours a night for a full week experienced a dramatic boost in cognitive performance and mood after they were allowed two full nights of recovery sleep.

Keep in mind that sleep debt is a cumulative measure. One night of no sleep shouldn’t upset your entire life, just as one night of good sleep won’t help much if you’re chronically underslept. Monitoring your total sleep debt over time is the only way to get an accurate picture of your sleep need.

Our second law, and the second “process” of the two-process model, is circadian rhythm.

You may have heard your circadian rhythm likened to your body’s internal clock. It dictates your ideal sleep and wake times, but it encompasses so much more than just sleep—it influences your eating habits, your energy fluctuations, and almost every bodily function. And it’s not just one clock, , distributed across your organ systems and cells.

You do have a master clock, however. It’s a group of neurons situated in the brain’s hypothalamus, collectively referred to as the suprachiasmatic nucleus. The nucleus is a hub for information, and is roughly attuned to the 24-hour light cycle caused by Earth’s orbit around the sun.

Each daily cycle, the nucleus takes in light and other stimuli, then responds by alerting the rest of the body’s clocks. This communication kicks off a variety of effects, from hormone production to changes in body temperature and mood. Your circadian rhythm thus produces a complex but observable pattern to your days.

Scientists visualize this pattern using a variety of markers. At 51����, we characterize your circadian rhythm as a graph of energy peaks and dips, with the peaks representing the times at which you’re primed to be alert and productive, and the dips representing the times at which your body is inclined to rest and refuel.

Obviously, bedtime is one such dip, and aiming for a consistent bedtime and wake time in accordance with your rhythm is one way to improve your sleep hygiene. You can also strategize around the day’s dips and peaks. Schedule tasks that require high concentration around your peaks, and relaxing activities or more passive work duties around your dips.

Another way to map your circadian rhythm is through core body temperature, which also undergoes cyclic changes throughout the day. In fact, body temperature is one of the most reliable markers of circadian functioning, and through which the suprachiasmatic nucleus oversees the rest of the body’s clocks.

Your circadian rhythm is a strange mix of inescapable and malleable. Its patterns occur no matter what—you can’t stop your circadian rhythm from cycling. But at the same time, your rhythm can be influenced and disrupted by external forces, light and temperature in particular. This is why we’ll recommend making changes to your environment so that it corresponds to the bedtime dip of your rhythm, thereby encouraging sleep.

Your genetics, too, play a role in how your circadian rhythm operates. Research indicates that all of us have a chronotype, or a circadian preference for sleeping and waking at certain times of day. , 30% are night owls, and 30% are somewhere in between the two. Age, gender, and exposure to environmental light , but your genes seem to be a major deciding factor as well.

The takeaway here is that working with your circadian rhythm leads to better sleep hygiene. If you work against it—staying up or waking up too late, or at varying times, for example—you’ll risk entering a dangerous state called . Circadian misalignment can lead to insomnia and other sleep disruptions, but it’s also associated with mood disorders, changes in metabolic function, and an increased risk of conditions such as diabetes and cancer.

To sum up: the two laws of sleep are based on minimizing sleep debt and adhering to your circadian rhythm. These are the levers you want to move to improve your sleep hygiene—the ones that drive your productivity, outlook, and physical wellbeing.

Both laws operate , but both determine the timing and depth of your sleep. Sleep debt cuts into your performance during the day as sleep pressure mounts and mounts, pushing you toward that rebalancing of the sleep homeostat. At the same time, your circadian rhythm nudges you toward an organic sleep and wake cycle that’s specific to you. Together, the two laws point you towards your ideal sleep duration and sleep regularity.

Why?

As your body prepares for sleep, its core temperature drops. Scientists think that this release of heat transitions us into sleep more fluidly, and that running a bit cooler—— as we snooze.

A cooler room mimics this change in body temperature and further encourages sleep. It has such a profound effect that sleep scientist Matthew Walker labels thermal environment as “perhaps the most under-appreciated factor determining the ease with which you will fall asleep tonight, and the quality of sleep you will obtain.”

Research backs him up: insomnia and poor thermoregulation , and people who sleep in relatively warm rooms upon waking. On the flipside, people with sleep disorders achieve when they sleep in 61-degree as opposed to 75-degree heat.

How?

Walker recommends 65 degrees Fahrenheit as the “sweet spot” for your bedchambers. He advises against going below 55 degrees or over 70 degrees. Most of the science pegs the ideal temperature range at 65-68 degrees.

There are thermoregulation hacks you can try, too. Sleeping with can support the cooling process. can also help, as it prompts a quick shift in core body temperature from hot to cold after you bathe.

Why?

Light is the primary signal interpreted by your suprachiasmatic nucleus (the master clock of your circadian rhythm). Our prehistoric ancestors set their biological clocks by the rise and fall of the sun, and our bodies have inherited the same tendency.

As the sunlight dims in the evening, the suprachiasmatic nucleus prompts the pineal gland in your brain to secrete , a hormone that preps the body for sleep. It lowers body temperature, blood pressure, stress hormones, and alertness. This period, which begins about 2–3 hours before you go to sleep, is known as dim light melatonin onset, or DLMO.

DLMO is considered . Whereas other markers, such as body temperature and heart rate, are susceptible to manipulation by a variety of outside factors, your DLMO typically remains unchanged. The only thing that can interfere with it is light.

Artificial lighting tricks your brain into thinking it’s still daytime. If there’s enough of it around you, your brain’s production of melatonin will be suppressed, and you won’t be able to get to sleep. Artificial light keeps our , and can mess with other aspects of your circadian rhythm, It’s even been shown to and in rodents.

“Light works as if it’s a drug, except it’s not a drug at all.” It’s so powerful as a circadian cue that has proven to be a viable treatment for people suffering from insomnia and other sleep disorders.

How?

You’ll definitely want to block out artificial light to the best of your ability as bedtime approaches.

A key point to understand: the light doesn’t have to be bright at all to have a severe impact on your ability to sleep. Artificial lighting tends to be , even if it appears dim to your eyes. Your clock radio, your desk lamp, even a nightlight—they all make a difference. of more than 10,000 teens found that those living in areas where outdoor artificial lighting (e.g. streetlights) was more prevalent not only slept less, but were also more likely to have anxiety or mood disorders.

So, aim for a pitch-black environment. Wear an for starters, but be aware that the human body . Turn off all the lighting in your bedroom, invest in a good set of blackout curtains or blinds, and embrace the dark.

The light exposure you get during the day has an effect on your sleep hygiene, too, and we’ll delve into how you should approach it in later sections.

Why?

Noise keeps you from falling asleep, and also disturbs the sleep you get. If it doesn’t wake you up completely, , thereby causing you to feel less rested and perform at a lower level when awake. that if you habituate yourself to a noise so that it doesn’t jolt you awake, you’ll still experience shallower, less rejuvenating sleep.

Interestingly, studies suggest that exposure to lots of noise during the day also , even when nights are perfectly quiet.

How?

Not all types of noise have the same disruptive qualities. Intermittent noise is to sleep than continuous noise, and in fact, blending noises together into white noise can promote better sleep. This is because white noise creates , an effect that disguises more disruptive noises with a consistent sound, such as static or the hum of an air conditioner. , white noise “reduc[es] the difference between background noise and peak noise.”

Complete silence, however, is golden. Carpets, floor coverings, curtains, and closed windows can . We also recommend using to fully protect your sleeping brain.

Your genetics, age, and recent sleep habits all affect the time you wake up in the morning. This is the opener to your day, and your opportunity to start strong.

RISE can help! RISE visualizes your grogginess zone on your energy schedule so that you’re aware of how long it lasts. You can also track your sleep quality. Just go to the "Energy" tab and add the "Sleep Quality" habit to your energy schedule. You'll get a reminder every morning (90 minutes after you wake) to gauge how you feel in relation to your sleep debt.

During this Time, You Should …

Be Consistent—Even on Weekends

• Waking up at a consistent, predetermined time each morning is one of the best ways to align with your circadian rhythm and keep your sleep routine steady. In , Walker argues that setting a regular bed and wake time is the single best practice you can adopt for improving your sleep.
• Sleep regularity is a separate metric from sleep duration, and has a profound impact on how you feel and perform. We know that “regular” sleepers than “irregular” sleepers, for example. These results suggest that even if you’re getting a good amount of sleep, sleeping at inconsistent times will still limit your functioning. The dual importance of sleep duration and sleep regularity mirrors the duality of the two laws: sleep debt and circadian rhythm.
• Committing to a sleep routine is no easy feat. You may be tempted to sleep in much later on weekends or the mornings after nights out. But letting your social clock overwhelm your biological clock leads to —a common type of circadian misalignment that causes worse sleep and more fatigue. of more than 300,000 people indicates that more than half of us are constantly shouldering social jet lag of an hour or more.
  

Push Through Your Sleep Inertia

• Experiencing sleep inertia—what Walker defines as “the carryover effects of sleep into wakefulness”—when you first wake up is totally normal. 51���� refers to this morning sleep inertia as the grogginess zone. It’s typified by and it can persist for up to 90 minutes.
  

Your energy levels are building in anticipation of your first peak. You may still be shaking off the sleep inertia of the grogginess zone, so this is a great time to get active and tell your body that the day has begun.

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Step into the Light

• Sunlight is thousands of times more strong than artificial light. (Direct sunlight has an illuminance of , whereas standard indoor lighting is about 500 lux or lower.) As we’ve mentioned, it’s also the most powerful signal received by your brain’s master clock, the suprachiasmatic nucleus. , “when it comes to regulating your circadian clock, 10 minutes of morning light is like the equivalent of four, five, or six hours of afternoon light.”
• Exposure to sunlight to suppress the sleep hormone melatonin, and raise concentrations of cortisol (a hormone that encourages alertness) and serotonin (a crucial neurotransmitter that regulates mood, and will later convert to melatonin when sleep is needed).
• Sunshine is warm, which counteracts the drop in body temperature you experience as you sleep and thereby assists you in waking up.
  

Consume Your Caffeine ASAP

• If you’re a coffee or tea drinker, you’re no stranger to the invigorating effects of caffeine. It , boosts your energy, and actually in the brain so that you don’t feel as much sleep pressure.
• However, caffeine stays in your system for a prolonged period of time. About 30 minutes after you consume it, caffeine . But it can take up to 10 hours to fully dissipate, keeping you from the rest you need later.
  

Consider Exercising

• Moving your body is that can help raise your body temperature and up your wakefulness.
• also helps you to fall asleep faster, increases sleep duration, and even prolongs the time you spend in deep sleep.
• Your exercise schedule should depend on what you most want out of your routine. Exercising in the morning wakes you up and adds energy to your day, but as you’ll see, there are different benefits to be gained from a later workout.
  

This is the first of your two daily energy peaks. Your focus, vigor, and tolerance for stress will be in top form. It’s time for some of your most high-stakes responsibilities.

During this Time, You Should …

Tackle Your Most Challenging Tasks

• Your are yet more circadian cues—they fluctuate dependably throughout the day. During your morning peak, you’ll be primed to really hone in on a given activity.
• Your are also apt to crest during this window.
• Recall that sleep debt cuts into your executive functioning abilities. If you haven’t been getting enough sleep, then your morning peak won’t be as productive.
  

Prioritize Stability

• Your circadian rhythm . Now’s a good time to take stock of your day and ensure that your routine is on track.
  

What goes up, must come down. Your first dip of the day typically corresponds to the afternoon, and is scientifically known as the postprandial dip. It’s that period of midday sluggishness that’s often linked to a post-lunch stupor—but, due to your circadian rhythm, it occurs whether or not you’ve eaten. This is the optimal time for low-stress work or relaxation.

During this Time, You Should …

Knock Out Easier To-Do’s

• Your attention and emotional resilience will be a bit more strained than they were during your peak. Let them rest by knocking out the more passive or simple items on your schedule.
• Just as it inhibits your peaks, . If you’re carrying a lot of it, expect to be extremely weary and unfocused during the dip.
  

Take a Break

• Think of your afternoon dip as a pit stop for refueling. You still have another peak left in your day, so don’t feel guilty for resting up.
• Take a nap! Naps can help you catch up on sleep debt and provide an additional, lasting jolt of energy. However, you’ll want to follow best practices to avoid the potential pitfalls of napping, such as debilitating sleep inertia.
  

This is your second and final energy peak of the day. Make it a last push—address projects that need lots of focus and effort. At home, it’s a good window for exercise, hobbies you’re passionate about, or quality time with your loved ones.

RISE can help! Just go to the "Energy" tab and add the "Evening Routine" habit to your energy schedule. Your most common evening activities are organized into your energy peak or wind-down time, with reminders to help you stay on rhythm each night.

During this Time, You Should …

Tackle Your Most Challenging Tasks (Again)

• Your attention is back up, and during this peak than during your morning one. Take advantage of this last cognitive spurt!
  

Consider Exercising

• Your body temperature is at its highest during this peak, and can push you to new heights of physical performance. Indeed, are broken in this window.
  

Hold Off on Eating Big Meals

• The closer you get to bedtime, the more a large meal poses a risk to your sleep. Some of the more overt physical effects of late-night meals include discomfort when lying down, indigestion, and acid reflux. But evening meals can also , making it more difficult to fall asleep, stay asleep, and get the ideal amount of REM sleep.
• The cautions against eating highly processed carbs especially before sleep, as these foods “may reduce serotonin levels and impair sleep.”
  

Avoid Alcohol

• Many people consider alcohol a sleep aid, when it’s anything but. , alcohol causes sedation, which is entirely separate from natural, healthy sleep. As it attaches to receptors in the brain, blocking neurons from sending out their signals, alcohol causes drowsiness and facilitates an easy slip into unconsciousness. However, your brainwaves in this unconscious state mimic those of someone under anesthesia, rather than someone who is moving organically through the stages of sleep.
• Alcohol also causes sleep fragmentation, which refers to sleep that is sporadically interrupted by periods of waking. This kind of uneasy sleep can’t fully reenergize your brain and body.
• Finally, alcohol suppresses REM sleep. Without this stage of sleep, your brain can’t dream, struggles to integrate memories, and diminishes the associations required for efficient learning.
  

Avoid Nicotine

• As a stimulant, nicotine discourages sleep—but, like alcohol, it also has . It fragments your sleep, inhibits slow-wave sleep, and increases fatigue during the day.
• People who don’t identify as smokers still experience sleep impairment if they consume nicotine. Meanwhile, chronic smokers are at a higher risk of noncontinuous sleep, and tend to wake up before their sleep need is met due to nicotine withdrawal.
  

The evening wind-down takes place in the 1-2 hours leading up to bedtime and is a key window of relaxation in anticipation of sleep. It’s how you ready your body for bed and begin the process of setting up a productive next day. Now is not the time to worry about additional work or obligations—instead, you should unplug and slow down, confident in the fact that recovery is a necessary part of productivity.

RISE can help! Just go to the "Energy" tab and add the "Evening Routine" habit to your energy schedule. Your most common evening activities are organized into your energy peak or wind-down time, with reminders to help you stay on rhythm each night.

During this Time, You Should …

Limit Your Light Exposure

• As we’ve discussed, light is the strongest of all circadian cues. If you bask in too much of it late at night, then your brain will be fooled into thinking it’s still daytime, and suppress its melatonin production. And the light doesn’t even need to be especially bright to have an impact--even and are strong enough to delay sleep. that, on average, evening exposure to such sources of artificial light can set your internal clock back by 2–3 hours.
• This problem is so pervasive that some people who think they suffer from insomnia may indeed be mislabeling the problem—they should look at their lights! Even a low-lit room (1-2% of the strength of daylight) .
• Light exposure doesn’t just lower melatonin production. It also inhibits REM sleep at night, and creates a lag of up to 90 minutes in the next day’s melatonin cycle, creating what Walker calls a “digital hangover” effect.
• Blue light is the foremost culprit of melatonin suppression, and it’s commonly exuded by television and phone screens.
  

Lower Your Temperature

• If you sync up with your body’s natural nighttime temperature decrease, you’ll fall asleep easier and experience more deep, rejuvenating sleep. Bathing before bed is an easy way to do this.
• During a bath or shower, the blood vessels near the surface of your skin dilate due to the water’s warmth. Once you’re out of the water, the dilated vessels are exposed to cool air, and promote rapid loss of body heat. You go from hot to cool very quickly, and this temperature differential aligns well with the loss of heat experienced as your body sleeps.
  

Mentally Decelerate

• Your wind-down should be a time for mental deceleration—or, in layman’s terms, slowing down your mind. For so much of the day, your brain is whirring and calculating, putting you in a state of cognitive arousal. It’s precisely this state that you want to avoid in the hours before you sleep.
  

Curb Anxieties and Intrusive Thoughts

• For many people, bedtime kicks off a cycle of anxious thoughts about what happened during the day, as well as what the next day holds. Entering a cycle of repetitive, worried thoughts is scientifically known as , and it threatens every aspect of your sleep. The same can be said of stress more generally—when you’re stressed about anything to the point of , sleep becomes almost impossible.
• What’s more, lack of sleep only compounds the stress you experience, as sleep loss and stress are locked in a bidirectional cycle.
  

Practice Relaxation Techniques

• Relaxing your body and mind before bed makes falling asleep far more effortless. That’s because relaxation techniques perform double duty: they diminish stress while simultaneously upping body awareness. With some trial and practice, you can discover which techniques put you out like a light.
  

Remember, your bedtime should fall within what we call in the RISE app your Melatonin Window. DLMO (dim light melatonin onset) marks the beginning of this phase. As your brain produces melatonin, all of your internal systems respond by getting ready to rest. Your body knows when it wants to go to bed—heed the call and prioritize sleep at this time.

RISE can help! RISE uses your sleep times to predict your Melatonin Window: the circadian phase when your brain is producing the optimal amount of melatonin to help you fall asleep and stay asleep. Sleeping according to your .

During this Time, You Should …

Stick to a Sleep Schedule

• Consistency remains a key aspect of sleep hygiene, especially now. Whereas your wake time is often dictated by work needs or other responsibilities, your sleep time might feel more loose. It shouldn’t!
  

Reserve Your Bed for Sleep and Little Else

• You want to build a strong association between your bed and sleeping. This association won’t solidify if you lay in bed while watching television, playing video games, or conducting conference calls. By cutting out these activities, you’re practicing what’s scientifically known as —saving your bed for the kind of stimuli that promote sleep, and only those!

If You Wake Up and Can’t Fall Back Asleep, Reset!

• What happens if you manage to fall asleep, but then wake up in the middle of the night feeling alert or jittery? In this scenario, you still want to preserve the association between your bed and sleep—and the best way to do that is to leave the bed while you’re feeling awake.