How to get better sleep—and why it matters

Roughly a third of U.S. adults get too little sleep, which may boost the risk of short- and long-term health problems. Here’s why sleep matters, how to determine your own sleep needs, and how to set yourself up for sleep success.

Aric Prather is a professor of psychiatry at the University of California, San Francisco, where he studies the effects of poor sleep on health and emotional well­being. Prather spoke with Nutrition Action’s Caitlin Dow.

Why sleep matters

Q: How can too little sleep affect our health?

A: Population studies fairly consistently support the idea that when people get insufficient sleep—typically categorized as less than five or six hours a night—they tend to be at increased risk for a whole host of negative health outcomes, including high blood pressure, cardiovascular disease like strokes and heart attacks, weight gain, type 2 diabetes, and early death.

There’s also accruing evidence linking short sleep duration to a higher risk of mild cognitive impairment and dementia, including Alzheimer’s disease. 

Q: But those studies can’t prove cause and effect, right?

A: That’s right. But the findings from experimental studies that manipulate sleep provide support for some of the biological pathways that would cause those health problems.

For example, when researchers bring people into the laboratory and allow them to sleep for, say, only four or five hours instead of eight, you can quickly see increases in blood pressure, markers of inflammation, or insulin resistance.

Q: So the body’s insulin becomes less able to admit blood sugar into cells?

A: Yes. And you can imagine that, over time, those perturbations could contribute to the downstream conditions like stroke, heart disease, type 2 diabetes, and so on.

Q: How does sleep influence mood and mental health?

A: Sleep disturbances—particularly insomnia— are a predictor of the incidence and recurrence of depression. Most people know that if we don’t get the sleep we need, life is harder. We may feel more anxious or irritable or depressed.

In our studies, when people sleep poorly or get less sleep than usual, they wake up in a worse mood. And they report feeling more stress for a given stressor. When people feel more sensitive to stressors, they have fewer emotional resources for coping with challenges or conflict. Sleep allows us to be resilient in our day-to-day lives.

Q: How does sleep affect the immune system?

A: We ran a study where we recruited 164 healthy adults and measured their habitual sleep for seven days before squirting rhinovirus—the virus that causes the common cold—into their noses.

People who slept six or fewer hours were about four times more likely to get infected and have symptoms compared to people who slept more than seven hours. That was true even though we controlled for factors that may make people more susceptible to catching a cold, like if they’re older or under stress or they smoke or get little physical activity. Sleep plays an important role over and above those factors.

Q: Does sleep affect the body’s response to vaccines?

A: Yes. We found that people who sleep fewer than six hours a night have a dampened immune response. They don’t make as many antibodies to the vaccine.

Q: So should people try to sleep more before and after getting a vaccine?

A: In one study, we found that shorter sleep duration reported on the two nights prior to getting the flu vaccine predicted fewer antibodies against at least one strain of the flu.

But to be sure that the timing of sleep matters, you’d need to restrict sleep in a lab before and after the vaccine and track how many antibodies people produce.

Of course, the most important thing is to get your vaccines, which still offer ample protection even if you’re not sleeping well.

Sleep needs

Q: How much sleep do adults need?

A: One of the biggest challenges in the sleep field is understanding this idea of “sleep need.” The question is: Need for what? Is it based on risk for disease or for life satisfaction? Maybe need differs for different outcomes and from person to person.

We do have population-level data that we can track to outcomes like cardiovascular disease, type 2 diabetes, or cognitive health. Based on that data, the American Academy of Sleep Medicine and the Sleep Research Society recommend that adults up to age 60 should get seven or more hours of sleep a night.

Q: What about people over 60?

A: The data wasn’t sufficient to make a clear recommendation, though we know that older adults get less sleep as they move into the seventh, eighth, and ninth decades of life.

Q: How can people know how much sleep they need?

A: Think about how much sleep you get when you feel your best. When do you not feel sleepy during the day? When do you feel like you can do all the things that you want to do? How much sleep do you get on vacation after a few nights of recovery?

In all likelihood, it’ll fall in the range of seven to nine hours. But sleep needs are personal. It’s not a one-size-fits-all approach. There are people who are outside those bounds and are healthy.

 Q: So six hours a night could be okay?

A: If people feel good, they’re energetic, and they’ve been this way for a long time, they shouldn’t be anxious about it. But if they’re sleeping in on the weekends, they’re probably accruing sleep debt during the week, which is a sign that they need more sleep.

I run an insomnia clinic, and I see some people who are anxious that they’re not getting enough sleep. They’re probably fine and just can’t produce more sleep. But the anxiety itself creates an insomnia that makes it harder for them to sleep.

Q: What about really short sleepers?

A: There are rare exceptions of people who need even less sleep. For example, familial natural short sleepers—the phenomenon is driven by genetics—need only, say, four hours of sleep. But there are many others who think they are those people who are absolutely not. Most of us need seven to nine hours a night to feel our best.

Sleep timing

Q: Should people aim for a consistent sleep schedule?

A: Yes. An important study published this year measured the sleep patterns of more than 60,000 people for a week, then followed them for about 8 years. People who kept more consistent sleep-wake times had about a 20 to 50 percent lower risk of dying during the study than people whose bedtime and wake times were all over the place. A consistent sleep schedule was actually a better predictor of dying during the study than how much sleep people got.

Q: Why would sleep timing matter?

A: Getting up at the same time every day helps to set your circadian rhythm. That’s the body’s master clock. The body’s functions—like appetite, digestion, and hormone release—work more efficiently if they have a steady rhythm.

When you wake up also starts the clock for when you get sleepy at night. The number one thing that we sleep medicine folks tell people who are struggling with sleep is to get up at the same time seven days a week. That doesn’t mean you can never sleep in. But if you’re having sleep problems, waking up at the same time each day is your first step.

Q: How much wiggle room is there?

A: If you can shoot for a wake time within half an hour, that’s good. But don’t let perfection be the enemy of good. Just do the best you can.

 Q: Do you focus more on wake times than bedtimes?

A: Yes. People who have insomnia can be anxious about their sleep. If you tell them that they need to be asleep at a certain time, they watch the clock and think, “Oh my god, it’s bedtime and I’m not getting sleepy.” At that point, forget it. You’re not sleeping.

But if you can manage to get up at the same time each day, over time you’ll start to get sleepy around the same time each night. 

How to get more slumber

Q: How else can people improve their sleep?

A: Don’t sabotage your sleep with poor sleep hygiene. For example, cut off your caffeine in the early afternoon. Limit your alcohol intake. Ensure that your bedroom is dark, quiet, and cool.

Q: Can you prime your mind and body for sleep?

A: I recommend that you have some sleep rituals because the brain likes predictability. It almost doesn’t matter what the ritual is as long as it’s relaxing. It could be your skin care routine, reading a book, listening to a podcast, tidying up the house. If it’s the same every night, your body will learn that this is when we wind down and go to sleep.

Also, don’t get into bed unless you’re sleepy, and don’t spend excess time in bed not sleeping. Your bed should only be used for sleep and sex. The bed can become a place of excess thinking, anxiety, or angst that is incompatible with sleep. If that happens, get out of bed, do something quiet until you begin to feel sleepy, then get back in. Over time, you’ll rebuild that association that the bed is for sleeping, which is fundamental to a predictable night of sleep.

Q: Should people disengage from their devices before bed?

A: That’s a common suggestion, but some of the reasoning behind it isn’t compelling. For example, you’ll often hear that you need to limit blue light exposure—which comes from indoor lights, TVs, phones, computers, and tablets—at night because it interferes with melatonin release.

Blue light matters, but I think for most people it matters less than the content that people typically consume on their devices, which is designed to keep you engaged and aroused. People put blue-light filters on their phone, thinking that’s the solution, and lo and behold, they still don’t sleep better because the light is only one part of the problem. I think the issue is less about the device itself and more about how you use it. And devices can help people get to sleep with meditations, music, and sleepcast stories.

I often tell people that if you like to watch TV before bed, watch TV—just not in bed. And maybe watch things that you’ve seen already. I like to watch The Office because I find it calming. That’s different than watching a crime series that ends in a cliffhanger that keeps you up and makes you want to watch more.

Q: If someone has tried all these changes and is still struggling to sleep, what do you recommend?

A: Bring it up with your primary care physician to see if there’s something obvious that can be addressed. Obstructive sleep apnea, for example, is woefully underdiagnosed.

But if your issue is falling asleep or staying asleep, I would urge you to get connected with a behavioral sleep medicine specialist before you consider medication.  Once you start taking sleep medications, it can be a slippery slope to dependence. People often get to the point where they think there’s no way they can sleep without meds. That’s not true, but it takes a lot of time to taper off.

Ideally, I recommend cognitive behavioral therapy that addresses the factors that drive insomnia. It’s equally—or more—effective than medication. The American Academy of Sleep Medicine recommends cognitive behavioral therapy as the first-line treatment, but it’s rarely the first thing people try.