NEW DELHI: Many people assume that sleeping longer automatically leads to feeling more refreshed, but experts say that is not always the case. In fact, waking up after nine hours of sleep can sometimes leave a person feeling groggier than after 7.5 hours.
The reason lies in the body’s natural sleep cycles, which typically last about 90 minutes. Each cycle ends in a lighter stage of sleep. If an alarm interrupts deep sleep, the brain remains flooded with adenosine—a chemical linked to sleepiness—resulting in a phenomenon known as “sleep inertia.” This can leave people feeling sluggish even after a long night’s rest.
Sleep quality also plays a major role. Nine hours of fragmented or interrupted sleep can be less restorative than seven hours of uninterrupted sleep. Factors such as alcohol consumption, a warm bedroom, a full bladder, sleep apnoea, or disturbances from a partner can significantly reduce sleep quality without fully waking a person.
Experts note that recovery sleep after a period of sleep deprivation may also contribute to grogginess. When the body is catching up on missed sleep, deeper and heavier sleep stages can make waking up more difficult.
Another key factor is the body’s internal clock, or circadian rhythm. Waking at a time that conflicts with an individual’s natural sleep pattern can leave them feeling tired despite getting enough sleep. Elevated melatonin levels and a delayed cortisol awakening response may further contribute to morning fogginess.
To reduce sleep inertia, experts recommend aiming for wake-up times that align with complete sleep cycles, maintaining a consistent wake schedule, exposing yourself to bright light shortly after waking, keeping the bedroom cool, and seeking medical advice if symptoms of sleep apnoea—such as snoring or waking with a dry mouth—are present.
According to sleep specialists, the quality and timing of sleep often matter more than simply increasing the number of hours spent in bed. (Agencies)
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