9 Tips to Improve Sleep Quality Today

Sleep is a critical period for bodily restoration, cellular repair, and metabolic waste clearance, processes that ensure optimal performance during wakefulness. For this reason, poor sleep quality is associated with an increased risk of many diseases and shorter life expectancy. Yet many people still underestimate its importance and adopt daily routines that quietly disrupt sleep quality and compromise their long-term health.

In this issue, we focus on sleep hygiene, a set of evidence-based actions proven to improve sleep quality. We share nine practical strategies you can start implementing today, along with clear explanations so you understand how they work and why they matter.

Before we dive into the practices, let’s first understand how falling asleep works and what actually defines a good night’s sleep.

Falling asleep is an interplay between two mechanisms: a sleep switch in your brain, which makes you feel sleepy, and a biological clock, which signals when during the day your body should sleep.

The body constantly uses energy to fuel metabolism, movement, and thinking. This energy comes from ATP (adenosine triphosphate). When ATP releases its energy, it is converted into a simpler molecule called adenosine. The more energy we use, the more adenosine accumulates in the brain.

As we go through the day and engage in energy-demanding activities, adenosine gradually builds up. This buildup is known as sleep pressure. The more adenosine accumulates, the stronger the drive to sleep. When adenosine binds to its receptors in the brain, it triggers the transition into sleep, effectively turning the sleep switch on.

Adenosine is cleared from the brain during sleep. When we don’t sleep enough, it is not fully removed, leaving elevated sleep pressure behind, which is why we feel sleepy the next day.

If we are constantly producing adenosine, why don’t we feel sleepy during the day? Because we also have a biological clock that regulates sleep and wakefulness. Our circadian clocks follow an approximately 24-hour cycle, and the central circadian clock relies primarily on light–dark signals.

During the day, light reaching the retina activates the central circadian clock (the Suprachiasmatic Nucleus), which stimulates wake-promoting brain regions and suppresses melatonin production. This alerting signal counteracts the buildup of sleep pressure and prevents the sleep switch from turning on.

As light decreases in the evening, the pineal gland produces melatonin, which removes this brake and allows sleep to occur.

Other environmental cues (“zeitgebers”), such as meal timing, social schedules, physical activity, alarm clocks, and screen exposure, can also shift or alter our internal clock.

Healthy sleep is a combination of sleep quantity and sleep quality, the latter defined by sleep architecture.

Sleep architecture refers to how sleep is organized throughout the night. Sleep is a rhythmic, cyclic process composed of cycles lasting approximately 90 minutes and repeated 4–6 times per night. Each cycle contains four stages: three stages of non–rapid eye movement (NREM) sleep: light sleep (N1), "deeper" or intermediate sleep (N2), and deep sleep (N3) and one stage of rapid eye movement (REM) sleep.

Each sleep cycle begins with N1, a brief transitional stage between wakefulness and deeper sleep. During this phase, awareness gradually decreases, though it remains easy to wake. N1 accounts for approximately 5% of total sleep time and serves as the brain’s entry point into the sleep process.

In this stage, eye movements stop, heart rate slows, and body temperature drops. It is the longest stage of a cycle and accounts for about 50% of total sleep time. N2 plays an important role in memory consolidation.

Deep sleep (N3) is the stage from which it is hardest to wake. It predominates in the first half of the night and accounts for 20–25% of total sleep. This is when much of the body’s physical repair and immune strengthening occur. This stage has been found to decrease with age.

During REM sleep, brain activity resembles wakefulness. We experience temporary muscle paralysis, rapid eye movements, and irregular heart and breathing patterns. This is when we dream. REM predominates in the second half of the night and accounts for about 20% of total sleep. It plays a key role in memory consolidation.

The duration of each stage shifts across cycles, and while each stage supports different aspects of restoration and cognitive performance, it is their coordinated interaction over multiple cycles that produces healthy, restorative sleep.

In healthy adults without sleep disorders, the most effective way to improve sleep quality is through behavioral and lifestyle practices that support both sleep quantity and sleep quality. Together, these practices are known as sleep hygiene. The core practices include:

In healthy adults, sleeping 7 to 9 hours per night supports sufficient sleep cycles and proper sleep architecture. Sleeping less than 7 hours may prevent the complete clearance of adenosine and sleep pressure, impairing full restoration. On the other hand, sleeping more than 9 hours can disrupt circadian rhythms and reduce exposure to zeitgebers such as light. Excessive sleep duration has also been associated with poorer health outcomes, including increased risk of mortality, diabetes, cardiovascular disease, stroke, and obesity.

This is one of the most important factors, as it helps stabilize internal biological clocks. It reduces daytime sleepiness and allows you to fall asleep and wake up more easily.

Aerobic exercise for about 30 minutes a day increases sleep pressure by increasing energy use and adenosine production. Exercise also helps regulate the circadian rhythm by reinforcing daytime alertness. For this reason, exercising too late at night or too close to bedtime is not advisable.

Limiting exposure to electronic devices and bright ambient lights in the evening helps prevent circadian rhythm disruption and supports melatonin production.

Caffeine resembles adenosine and blocks its receptors in the brain, delaying sleep onset and reducing sleep maintenance. While this is why many people use caffeine, it remains in the body for about 6 to 7 hours, pushing sleep onset later when consumed in the afternoon or evening. Caffeine has also been shown to alter sleep architecture by reducing stage N3 sleep, which is crucial for physical recovery, and increasing stage N1 sleep, which should occupy only a small portion of the night.

Although alcohol can act as a sedative, it disrupts sleep architecture. It often causes awakenings in the second half of the night, increases early deep sleep as the body compensates for disruption, and delays and reduces REM sleep. The result is poorer sleep quality and shorter total sleep duration.

Eating is also a zeitgeber and can signal to the body that it should remain awake, delaying sleep onset. In addition, digestion increases blood flow to the gastrointestinal tract and raises heart rate, which can delay entry into N1 sleep and the transition to N2.

Focusing on the breath, a mantra, or a body sensation can shift the nervous system from sympathetic to parasympathetic activity. In other words, it reduces alert and stress signals while increasing calming, restorative signals that support sleep initiation. 

Reducing zeitgebers such as noise and light, and maintaining a quiet, dark, and cool environment promotes deeper and more restorative sleep.

For many healthy adults, productivity-driven lifestyles often come at the expense of sleep. Although sufficient duration is fundamental, consistent daily habits can significantly improve sleep quality and next-day performance. Understanding the biology of sleep helps us value and safeguard it.