For years, sleep duration has been treated as the gold standard of rest. Adults are advised to get seven to nine hours of sleep each night—and many assume that exceeding this benchmark should guarantee energy and alertness. But for a growing number of people, even 9–10 hours of sleep fails to prevent morning exhaustion.
According to Dr Manav Manchanda, Director & Head of Respiratory, Critical Care & Sleep Medicine at Asian Hospital, the problem often lies not in how long we sleep, but how well the body is able to restore itself during sleep.
“The appropriate length of sleep is not necessarily restorative sleep,” says Dr Manchanda. “Persistent fatigue despite long sleep hours usually points to factors that disrupt sleep quality—often without the person realising it.
When sleep duration isn’t the problem
Several underlying medical conditions can fragment sleep without obvious awakenings.
“Sleep disorders such as obstructive sleep apnea, restless legs syndrome, or periodic limb movement disorder can repeatedly disturb sleep architecture, even if the person believes they slept through the night,” explains Dr Manchanda.
In such cases, the brain is unable to cycle properly through the stages of deep and REM sleep—the stages responsible for physical recovery, hormonal balance, and cognitive restoration.
Beyond sleep disorders, systemic health issues can also play a role.
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“Hormonal imbalances, thyroid disease, anaemia, chronic infections, and metabolic conditions like diabetes are common medical causes of unexplained fatigue,” Dr Manchanda notes.
Mental health is another major contributor. Anxiety, depression, and chronic stress can prevent the brain from fully disengaging at night, keeping sleep light and non-restorative, he adds.
The role of sleep quality
Sleep quality refers to the continuity, depth, and uninterruptedness of sleep—not just its duration.
“People may technically sleep for nine or ten hours, but frequent micro-awakenings, shallow sleep, or insufficient deep sleep can leave them feeling unrested,” says Dr Manchanda.
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Conditions such as sleep apnea cause brief interruptions in breathing that lower oxygen levels and repeatedly jolt the brain awake—often without conscious awareness. Similarly, insomnia, chronic pain, or acid reflux can silently disrupt sleep cycles.
Environmental factors also matter. “Noise, light exposure, uncomfortable room temperature, and poor sleep hygiene can significantly reduce sleep quality,” he adds.
When restorative processes are compromised, the body struggles with hormonal regulation, immune function, memory consolidation, and tissue repair—leading to morning fatigue, headaches, poor focus, and mood changes.
Are you sleep deprived too? (Photo: Freepik)
How lifestyle habits undermine restorative sleep
Modern lifestyles are among the major threats to sleep quality. “Chronic stress raises cortisol levels, which makes it harder to enter deep sleep stages,” Dr Manchanda explains.
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Late-night screen exposure suppresses melatonin production and delays the body’s internal clock. Irregular sleep timings—such as sleeping late on weekends or inconsistent bedtimes—further confuse circadian rhythms.
“Heavy meals, caffeine, alcohol consumption, and physical inactivity also negatively affect sleep quality,” he says. “More sleep hours cannot compensate for disrupted biological rhythms.”
Consistency, stress management, and daytime activity play a crucial role in making sleep restorative rather than merely long.
When persistent fatigue needs medical attention
Occasional tiredness is normal—but weeks of persistent morning exhaustion are not.
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“If fatigue continues despite adequate sleep duration and good sleep hygiene, medical evaluation is essential,” advises Dr Manchanda.
Warning signs include loud snoring, pauses in breathing during sleep, morning headaches, excessive daytime sleepiness, poor concentration, and mood disturbances.
Left untreated, chronic sleep problems can have serious consequences. “Poor sleep quality and untreated sleep disorders are linked to hypertension, heart disease, diabetes, obesity, depression, and weakened immunity,” Dr Manchanda warns.
Early diagnosis can uncover reversible causes and prevent long-term complications. “Professional assessment allows us to identify the root issue and guide treatment—whether through lifestyle changes, medical therapy, or sleep-specific interventions,” he adds.
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