When you were in your 20s, you probably could stay out late, fall asleep the minute you got home, and stay that way for at least eight hours (unless the alarm went off earlier for work). But as you age, this long, uninterrupted slumber seems harder to come by.

For the average adult, seven to eight hours of sleep per night is considered healthy. Yet older adults often struggle to get the recommended amount of sleep even if they go to bed at a reasonable hour. If you’re one of them, don’t beat yourself up over it — it’s mostly biological, and there are ways you can mitigate it. 

Here’s why your body naturally wakes you up earlier as you age. 

Off the (Internal) Clock

There are two main types of sleep patterns: REM (rapid eye movement) and non-REM (non-rapid eye movement). These are linked to electrical activity in your brain. REM sleep is when most dreams occur and your brain activity is more active, while non-REM includes deep sleep. This is when your brain activity slows down, which helps you feel refreshed in the morning.

You cycle through REM and non-REM sleep every night, usually three to five times. Children’s sleep cycles last about 50 minutes, while adults’ last about 90 minutes. As you age, you have fewer periods of “slow-wave sleep,” the deepest type of non-REM sleep you can have. Since your sleep is lighter, you’ll tend to get up earlier.

Two different body processes control your sleep-wake cycles: sleep-wake homeostasis and your circadian biological clock, also known as your internal clock. The first gives you energy when you wake up but chemically creates a need for sleep the longer you’re awake. The second is a natural 24-hour clock that controls the times you feel sleepiest (usually 2 a.m. to 4 a.m. and 1 p.m. to 3 p.m., though it varies from person to person).

The two systems work together. However, as you age, the time period during which your internal clock enables sleep shrinks. It also tends to move up further into the night, in a phenomenon called advanced sleep phase syndrome (ASPS). 

You may find yourself waking up earlier in the morning and falling asleep earlier in the night. The reason for this shift in your internal schedule ranges from physical and behavioral changes to hormonal changes and medical issues. The brain’s internal clock is located in your hypothalamus, and age affects its functionality. ASPS also occurs because older adults are often less physically active and receive less sunlight.

Sunlight is a key part of your body’s melatonin production, and melatonin is an important sleep-regulating hormone. When it gets dark out, your brain sends a message to the pineal gland to release the hormone so you’ll start to feel sleepy. Compounding the issue is that, as you age, your body produces less melatonin.

It’s not the only hormone to affect sleep as you get older. Women who have undergone menopause may find the decline in estrogen and progesterone can cause night sweats and hot flashes — conditions that may make sleep harder to come by.

Everybody gets older, but there are things you can do to help improve your sleep. These include regular exercise, avoiding evening or late afternoon naps and caffeine, and improving your sleep environment and bedtime routine, such as taking a warm bath or reading a book at night.

It’s also important to follow a regular bedtime routine and schedule, even on weekends or when traveling. Even if you find yourself getting up earlier than you’d like, at least the sleep you’ll get will be better quality.

Any chef will tell you there’s no crying in the kitchen — unless you’re chopping onions. The seemingly normal task can reduce even the most stoic cooks to tears in seconds.

The phenomenon can’t be explained by the veggie’s strong smell. If that were the case, other pungent foods (think stinky cheeses) would also make you tear up. So why do onions make you cry? And how can you make them stop long enough for you to finish cooking without turning into a blubbering mess?

Tear Gas

Like garlic, onions have alliinase enzymes and amino acid sulfoxides stored in their cells. They’re part of the defense mechanism that protects the plant from hungry critters while it grows underground. 

If an unsuspecting animal were to bite into a vulnerable baby onion and rupture its cells, it would set off a chain of chemical reactions: The enzymes convert the sulfoxides into sulfenic acid, which then converts into an irritating gas known as syn-Propanethial-S-oxide. 

Chopping an onion produces the same effect — for all the onion knows, your knife is the incisor of a hungry gopher. Once it’s cut, the veggie produces its defensive gas, which wafts into the air and triggers a burning sensation in your eyes. It’s not dangerous, but it can be uncomfortable.

Your brain responds by activating your lacrimal glands, which release a flood of tears — not because you’re upset, but to physically clear the sulfuric chemicals away. These reflex tears, as they’re known, respond to irritants such as smoke or chopped onions by flushing your eyes before draining through tiny ducts in the inner corners of your eyelids.

When they can’t drain quickly enough, the tears will run down your cheeks as if you just finished watching Titanic. You may even get a runny nose.

No More Tears

Some food experts swear by the tearless onions now sold by select retailers. They’re not GMO (genetically modified in a lab). Instead, they’ve been cultivated through crossbreeding over decades. These sweet onions usually are only available at certain times of the year.

If you’re cooking with a standard supermarket onion, there are tips you can try to reduce irritation to your eyes. Always use a sharp knife; the finer the blade, the fewer cells you’ll rupture. Avoid cutting the root of the onion, as it holds the highest concentration of sulfuric compounds that make you tear up.

Chilling the onion in the fridge for an hour or so before slicing it can slow the chemical reactions and reduce the irritants that travel into the air. Some experts also recommend soaking onions in a bowl of cool water before it’s time to chop. 

Other tricks include placing a wet paper towel beside your cutting board to absorb the irritants or lighting a candle nearby to burn away the gas before it reaches your eyes.

If none of these tips work, you can always wear goggles. No, really.

You’re not the only one who might fall asleep while cozying up on the couch — your feet are also prone to a quick snooze. Feet are finicky about sitting positions, causing them to doze off momentarily when you trade proper posture for a more comfortable lounge position.

Your foot isn’t sleeping of course, and the numbing sensation isn’t actually the feeling of blood rushing back into your arteries, as the common myth suggests. Instead, it indicates an internal pause button between the nervous system and one of its most important collaborators.

Getting on Your Nerves

Your feet contain thousands of nerve endings, all connected to five larger nerve branches running up your legs toward the rest of your body. Temporary numbness, which doctors call “transient paresthesia,” occurs when pressure squeezes these nerve branches, momentarily pausing their signals to the brain. 

This results in a loss of sensation in your foot. If your nerves were hoses spanning your body, paresthesia would be like a kink that blocks water from flowing. Stepping on a hose also cuts off water — in that sense, it’s possible for you to “step” on your own nerves, trapping them under the pressure of your own body.

While the initial numbness comes from your nerves losing communication with the rest of the body, the “pins and needles” feeling becomes more prominent after you take the pressure off. This tingling happens because nerves misfire as they wake back up, creating a rush of odd sensations that aren’t quite pain or itchiness.

The sensation of limbs falling asleep can also be caused by reduced blood flow, as nerves can’t function without the oxygen and nutrients carried by your blood. When this happens, nerves aren’t just unable to transmit their signals — they can’t generate any in the first place. 

While losing blood flow to your foot might sound concerning, it doesn’t generally cause a permanent impact and, just as with nerve pressure, can be relieved almost immediately by moving or changing positions.

Some chronic conditions might also result in limbs frequently falling asleep, including vitamin deficiencies, diabetes and prediabetes, and spinal injuries. Since these causes are not connected to sitting position, they occur more randomly and might last longer or not go away once you move. 

Temporary numbness from sitting awkwardly and similar causes isn’t typically concerning medically, though. While not literal, “falling asleep” is a good metaphor because it describes the generally benign and temporary nature of this phenomenon. 

Luckily, your feet are light sleepers and can wake up quickly by adjusting your sitting or sleeping position.

Remember when you were a kid and a friend or sibling poked and wiggled their fingers into your ribs? Before you even had time to think, you were laughing. Not just smiling — real, uncontrollable laughter that came out in bursts while you twisted away, tried to block their hands, and maybe even protested that it was not funny.

Tickling sits in a strange middle ground that can feel part playful, part irritating, and sometimes even stressful. So why does something that’s not really funny make you laugh, whether you want to or not?

Mixed Emotions

Unlike the laugh that follows a joke from your favorite comedian, laughter from tickling is an involuntary reflex, which is why you may find yourself giggling even while desperately trying to make the tickling stop.

Though it’s a single organ, your brain is made up of different regions dedicated to different functions. When someone tickles you, sensory receptors in your skin send signals to your brain. 

Among the regions involved is the somatosensory cortex, which processes touch, including where and how strongly you’re being touched. Other parts of the brain associated with emotion and defensive responses (including your fight-or-flight reflexes) also become active. 

Like too many cooks in the kitchen, each relevant part of the brain is telling you how to feel at once. The result can be a peculiar combination of laughter, squirming, flinching, and trying to escape.

Laughter Is the Best… Defense?

Scientists still don’t know exactly why this particular kind of touch produces laughter, but one leading idea is that it may be tied to ancient defensive behavior. The ribs, neck, underarms, and feet — the areas most sensitive to tickling — are also some of the body’s more vulnerable regions. When someone unexpectedly touches one of these areas as part of tickling, your reaction isn’t just to laugh: You also pull away or try to protect yourself.

That combination of moves has led some researchers to suggest that ticklish laughter may have evolved as a signal of submission to an aggressor. In other words, the laughter could be “saying uncle,” communicating something like “You got me,” in order to defuse or shorten an encounter before it turns into something more dangerous. (Unlike with bears, playing dead does not work with tickle monsters.)

That could help explain the strange contradiction of tickling: You can laugh uncontrollably while simultaneously wanting it to stop and trying to escape. In this case, the laughter isn’t necessarily a sign of pleasure at all.

That said, some scientists think that tickling between parents and babies or young children can play a positive role in bonding. But if you’re trying to make a fellow adult feel good, telling a funny joke is probably the better move.

When you visit the doctor for a yearly checkup, pre-op appointment, or really anything else, one of the first things you can expect they’ll do is check your blood pressure. And when they do, you’re given two numbers as a result (X over Y).

The top number is your systolic blood pressure, and the bottom is diastolic — but what do they actually mean, and what information do their ranges give about your health?

Systolic vs. Diastolic Numbers

A full heartbeat consists of multiple steps, all occurring within about a second for a heart rate of 60 beats per minute (a normal resting heart rate for adults). The heart muscle contracts to squeeze blood into and through your arteries, like how you squeeze a turkey baster to pump drippings. The heart then momentarily relaxes as more blood comes in so that it can squeeze again, which would be the start of the next heartbeat.

Your blood pressure has two numbers because they are measurements of the same artery at two different times within the span of that one second. The first, or top, number is your systolic blood pressure. This represents how much pressure your blood is pushing on your artery walls as your heart is squeezing. As blood is pumped, healthy arteries stretch and expand before settling back into shape.

The second, bottom number is your diastolic blood pressure, taken while the heart muscle is relaxed. This “relaxed” period is the silence you hear between two heartbeats (which is why your heart has less time to relax when your pulse is high). Like the top number, the bottom number also represents the pressure your blood exerts onto your artery walls, though at this point they should also be relaxed, like a toothpaste tube you’re not currently squeezing.

The numbers themselves are given in “mm Hg,” which stands for “millimeters of mercury.” That’s because early blood pressure measurements were taken by seeing how many millimeters of liquid mercury were pushed up a tube by the same pressure pushing against your arterial walls. The name has stuck around, but modern equipment keeps the poisonous metal out of the equation.  

The reason high blood pressure is considered a serious health issue is because it represents the force your blood is putting upon your arteries and vessels throughout your body. These tiny, fragile parts of the body can be damaged as they’re pushed open over and over with more force than needed, causing all kinds of problems, from aneurysms to kidney issues. 

Because your diastolic pressure is taken while your heart is relaxed, it tells the doctor more about the current state of your arteries, including their elasticity. Ideally, when blood isn’t being pumped through them, they’re springing back into a narrower shape, like a rubber band returning to its normal size after you stretch it.

According to the American Heart Association, the systolic number can offer more information in regard to risk factors for heart disease for anyone over 50, but both numbers are equally important when it comes to diagnosing high blood pressure, also called hypertension.

What’s a Normal Range?

Now that you know what each number represents, it’s helpful to also be aware of when numbers are “normal,” versus concerning and maybe a sign that you need to talk to your doctor. A normal, healthy blood pressure range is considered to have a systolic number less than 120 and a diastolic number less than 80. Slightly elevated numbers, where your systolic is between 120 and 129 but diastolic still less than 80,  are outside of the normal range, but not  considered hypertension yet. 

Hypertension — the formal term for high blood pressure — has four distinct stages, starting with stage one, which includes systolic numbers between 130 and 139 or diastolic numbers between 80 and 89. Stage four, which includes systolic numbers higher than 180 and/or diastolic numbers higher than 120, is the most severe and considered a hypertensive emergency that needs to be treated immediately.

Your blood pressure can also be too low if your reading is less than 90 over 60. It’s typically not considered harmful unless you’re also experiencing symptoms such as confusion, dizziness, nausea, fatigue, blurred vision, heart palpitations, and more. Only a healthcare professional can provide accurate guidance on concerns about low blood pressure.

Knowing your blood pressure gives you and your doctor a lot of useful information when it comes to your health. That’s why, in this case, two numbers are better than one.