While occasional lack of sleep may not seem like a big deal, its impact can be intense and its effects can linger. And if you make it a habit, not sleeping enough can have severe consequences for your health.
“As a society, as families and as individuals, we have not yet fully appreciated the importance of sleep,” says Terry Cralle, RN, a certified clinical sleep educator based in Fairfax, Virginia. “Sleep, along with diet and exercise, constitutes the very foundation of good health.” These health factors so interconnected that each of them needs to be a priority, she adds.
After 24 hours of no sleep, stress hormones cortisol and adrenaline increase to compensate for the fatigue you’re battling and help you function, says John Cline, PhD, a licensed clinical psychologist and fellow of the American Academy of Sleep Medicine.
“The brain is trying to cope with not having its opportunity to rejuvenate itself, so we have these heightened stress hormones to keep the body activated,” says Dr. Cline.
The consequences of sleep deprivation at 24 hours are comparable to the cognitive impairment of someone with a blood alcohol content of 0.1 percent. (For reference, in most states, the alcohol limit to legally drive is 0.08 percent.) You may experience reduced reaction time, slurred speech, and slowed thinking.
That level of cognitive impairment could be enough to spell danger, depending on what you’re doing. Cline compares it to the increased risk of a car accident due to drowsiness after someone works an overnight shift.
“Judgment is affected, memory is impaired, and there’s deterioration in decision-making ability and eye-hand coordination,” says Cralle. You also tend to be more emotionally reactive, attention is decreased, hearing is impaired, and there’s an increase in your risk of death from a fatal accident, she says.
At this point, high levels of inflammatory markers in the bloodstream are common, which can eventually lead to cardiovascular disease and high blood pressure, says Cralle.
During a typical healthy night of sleep, blood pressure drops by around 10 to 20 percent.
In fact, blood pressure dropping less than 10 percent overnight is a sign of an irregular blood pressure pattern.
But if sleep is chronically interrupted or not happening at all, remaining at an elevated blood pressure may be a risk factor for hypertension.
Additionally, this level of sleep deprivation affects hormone balance, which can result in emotional dysregulation. As your body keeps pumping cortisol into your bloodstream, raising your heart rate and blood pressure to keep you alert, the additional stress can increase feelings of anxiety and mood swings, says Cline.
If you were cranky, on edge, and zombie-like before, those symptoms will likely worsen after 36 hours with no sleep, says Cline. “Everything going on at 24 hours is going to be worse at 36 hours,” he says.
Cognitive impairment grows more severe as well. You’re likely to feel sluggish and experience delayed reaction times, foggy memory, and an inability to concentrate, learn new information, and process social cues, says Michelle Drerup, PsyD, a psychologist and the director of the behavioral sleep medicine program at Cleveland Clinic.
At the 48-hour mark, you’re dealing with “extreme sleep deprivation,” says Dr. Drerup.
The body begins to compensate by shutting down for “microsleeps,” 3- to 15-second bursts of rest during which your brain switches off, says Drerup. Your eyes don’t necessarily close, and you may not be consciously aware of what’s occurring, but your brain is going offline for seconds at a time.
Brain waves measured by electroencephalogram suggest that during microsleep, there are both similarities and differences to the four
stages of sleep.
After two days of no sleep, you can count on increased irritability, anxiety, foggy memory, and impaired thinking, says Hussam Al-Sharif, MD, a pulmonologist and sleep medicine specialist at Mayo Clinic in Eau Claire, Wisconsin.
Some people may even experience hallucinations, seeing or hearing things that aren’t really there. “Some people feel depressed, and some might become euphoric,” says Dr. Al-Sharif.
Expect significant deficits in concentration, motivation, perception, and other higher mental processes after so many sleepless hours, says Cralle.
You’re going to feel pretty miserable and dysfunctional with this much sleep deprivation, adds Cline. “The brain is fighting against wanting to shut down, and that’s going to create a really fragile emotional state,” he says.
Microsleeps also increase in length and frequency at this level of sleep deprivation, which Cline describes as a protective response by the body. But those fleeting moments of involuntary rest are incredibly risky, especially if you’re behind the wheel, operating heavy equipment, or responsible for make-or-break decisions at work.
This point of sleep deprivation is also when the mind is ripe for hallucinations, delusions, and paranoia, says Al-Sharif.
Chronic poor sleep puts us at increased risk of serious medical conditions, such as
obesity, heart disease, and
diabetes.
During sleep, the body secretes hormones that control appetite, metabolism, and glucose processing. Poor sleep can lead to an increase in the body’s production of cortisol.
Skimping on sleep seems to throw other hormones out of whack as well. For instance, less insulin is released after you eat, and that, along with increased cortisol, may lead to too much glucose in the bloodstream and thus an increased risk of type 2 diabetes.
While sleep needs may vary from person to person, it’s recommended that adults get between seven and nine hours of sleep each night.
And contrary to popular belief, sleeping an extra hour or two on a weekend cannot make up for sleep lost over the course of a busy week.
Instead, it could throw off your internal body clock and possibly lead to
insomnia on Sunday night. You’re better off sticking to a consistent
sleep schedule.
- The mental and physical effects of going without sleep for 24 hours include elevated cortisol levels, impaired coordination, and poor memory and judgment.
- Not sleeping for 48 hours is considered extreme sleep deprivation, and the body copes by shutting down for involuntary episodes of sleep called microsleeps that can be dangerous should they occur at the wrong time.
- A lack of sleep for 72 hours often results in significant deficits in concentration, motivation, and perception, as well as potential hallucinations, delusions, and paranoia.
- It’s recommended that adults get between seven and nine hours of sleep each night and stick to a consistent sleep schedule to reap the many health benefits of high-quality sleep.
Rachel Green
Rachel Davis
Derek Schulz
Sophia Martinez
Dr. Amara Okafor