26th June 2026 – (Singapore) The long‑standing belief that eight hours in bed guarantees a restorative night is increasingly being challenged by scientists, who warn that both modern lifestyles and the natural ageing process are undermining the body’s ability to achieve truly restorative sleep.
In sleep laboratories, researchers have identified a consistent pattern: many people record a normal total sleep duration yet spend less time in slow‑wave sleep, the deep stage most closely associated with tissue repair, immune function and metabolic recovery. As a result, individuals may technically sleep for eight hours but still wake feeling unrefreshed.
Sleep specialists argue that the issue extends beyond personal habits. Orfeu Buxton, a behavioural health researcher at Pennsylvania State University, has said that ending the workday does not automatically signal safety to the brain. For restorative sleep to occur, stress hormones such as cortisol must decline, parasympathetic pathways must activate and the body’s circadian clock must fully transition into night mode. When those signals fail to align, the nervous system remains on alert.
Digital stimulation appears to compound the problem. In her book Dopamine Nation, Stanford psychiatrist Anna Lembke contends that constant exposure to digital rewards leaves the brain’s craving circuits overstimulated and restless even after devices are switched off. A 2025 study published in Frontiers in Psychiatry found that higher levels of smartphone dependence were strongly linked to poorer sleep quality and increased psychological distress, even among individuals who set aside adequate time for rest. The findings suggest that simply protecting eight hours for sleep may not be sufficient if the underlying physiology of recovery is not engaged.
Researchers now describe sleep health as encompassing not only duration but also timing, regularity and depth. Artificial light at night can delay circadian rhythms while simultaneously activating alertness pathways in the brain, raising cortisol levels and masking sleepiness. Notifications, unresolved work demands and habitual scrolling may prevent the nervous system from receiving a clear signal that it is safe to disengage from threat monitoring.
Neuroimaging studies reinforce this view, showing continued activation in the brain’s salience network — the circuitry responsible for detecting threats — even in the absence of immediate stimuli. In laboratory settings, incomplete recovery is measurable through slower nighttime declines in cortisol and reduced heart rate variability, an indicator of diminished parasympathetic activity.
Sleep is also tightly regulated by the body’s internal clock. The brain anticipates rest within a specific biological window, and attempts to sleep outside that period can result in lighter, more fragmented rest. This becomes particularly relevant with age. After 60, sleep architecture changes naturally: deep sleep diminishes, awakenings become more frequent and circadian timing shifts earlier. Many older adults feel sleepy earlier in the evening and wake earlier in the morning, often struggling to return to sleep.
Medical experts note that, in later life, eight hours in bed may include significant periods of light sleep rather than sustained restorative phases. Deep sleep, crucial for immune strength and memory consolidation, declines with age. Consequently, some individuals may feel more refreshed after seven hours of high‑quality sleep than after eight or nine hours of broken rest.
Undiagnosed health conditions further complicate the picture. Obstructive sleep apnoea becomes more common with age and can repeatedly interrupt breathing during the night, reducing oxygen levels and fragmenting deep sleep. Chronic illnesses such as diabetes, thyroid disorders, heart disease and depression may also impair sleep quality or cause daytime fatigue regardless of time spent in bed. Certain medications, including some antidepressants and blood pressure treatments, can suppress rapid eye movement sleep or contribute to frequent awakenings.
Lifestyle shifts following retirement may also reduce sleep efficiency. Lower levels of physical activity, reduced exposure to daylight and increased time indoors can weaken the body’s sleep drive. Research in sleep medicine journals indicates that even moderate daily exercise, such as walking, improves sleep consolidation and depth.
The notion that everyone requires precisely eight hours of sleep has historical rather than scientific roots, dating back to early 20th‑century labour standards. Current guidance from sleep authorities generally recommends seven to eight hours for adults over 60, while acknowledging considerable individual variation. Experts increasingly advise focusing less on a fixed number and more on whether one feels alert during the day, falls asleep easily and remains asleep for most of the night without excessive reliance on caffeine.
Persistent exhaustion, however, should not be dismissed as a normal feature of ageing. Sudden or severe fatigue, loud snoring accompanied by choking sounds, memory decline, depression or physically acting out dreams may indicate underlying sleep or neurological disorders and warrant medical assessment.
Clinicians emphasise that most sleep disturbances in later life are manageable once identified. Consistent sleep schedules, morning light exposure, regular exercise, limiting alcohol near bedtime and reducing evening screen use can all strengthen circadian rhythms and improve deep sleep. When symptoms persist or worsen, professional evaluation is essential.