The American Heart Association has concluded that most adults can safely consume up to 400 milligrams of caffeine per day – the equivalent of roughly five 230‑millilitre cups of black coffee – and that this level may even be associated with a lower risk of cardiovascular disease. The same analysis, however, warns that high‑dose sources such as energy drinks, which can contain three to four times more caffeine than regular coffee, have been linked to abnormal heart rhythms in people otherwise considered low‑risk and “should be avoided”. The findings, drawn from a review of multiple data sets, underscore that caffeine is not a uniform substance: a typical cup of coffee delivers 9.5 to 20.6 mg of caffeine per fluid ounce, whereas some energy drinks pack 40 to 69 mg per ounce.

Viewed from Jakarta, Indonesia’s Ministry of Health has detailed how chronic sleep deprivation directly damages the cardiovascular system. Insufficient sleep disrupts the autonomic nervous system, raising blood pressure and increasing the risk of arrhythmias, including ventricular tachycardia. It also triggers systemic inflammation, marked by elevated interleukin‑6 and C‑reactive protein, which can damage blood‑vessel linings and accelerate atherosclerosis. The ministry notes a U‑shaped relationship: both sleeping less than five to six hours and more than eight hours per night are associated with a higher risk of diabetes mellitus, while long working hours – above 67 per week – correlate with elevated coronary heart disease mortality. Separate reporting adds that staying up late disrupts hunger‑regulating hormones, leading to weight gain, and weakens immune function.

At the cellular level, researcher Dr Pradeep Mahajan describes a phenomenon often overlooked: “cellular fatigue”. Mitochondria, the energy‑producing structures inside cells, become less efficient when the body is subjected to chronic stress and poor sleep. Stress hormones keep the body in a state of high alert, diverting energy away from repair and restoration. Over time, this drains cellular reserves, leaving individuals exhausted even after a full night’s rest. Dr Mahajan stresses that persistent fatigue should not be normalised; it is a warning that the body’s energy systems are malfunctioning and require timely medical attention.

For adolescents, the stakes are developmental. Prof Dr Aman Bhakti Pulungan, a paediatric endocrinologist in Indonesia, explains that growth hormone and other puberty‑related hormones are released predominantly during deep sleep and the rapid eye movement phase. Teenagers aged 12 to 18 need eight to nine hours of sleep, and he advises a bedtime no later than 9 p.m. to align with the body’s circadian rhythm. “Deep sleep cannot be discounted,” he says, warning that weekend catch‑up sleep does not compensate for lost hormonal windows.

Amid the search for countermeasures, some researchers are investigating whether creatine, a compound that helps replenish the brain’s energy currency adenosine triphosphate, can alleviate the brain fog that follows a sleepless night. Neurologist Khalid Al Saffar of Medcare Al Safa in the UAE notes that during sleep deprivation the brain struggles to maintain optimal energy levels, and creatine may help preserve attention and processing speed. However, he and colleague Dr Sheril Susan Koshy caution that the evidence remains limited and inconsistent, and that it would be “premature” to recommend large single doses based on one study. The American Heart Association similarly stresses that there is no “one‑size‑fits‑all” strategy for caffeine, with individual responses shaped by age, genetics and health conditions. Further large‑scale trials are awaited.