ChaiFM

1) Wired But Tired How can you be simultaneously tired yet wired – the paradoxical feeling of being physically exhausted but mentally unable to switch off? Blame your stone‑age brain. Your “human stress response” evolved to respond to short-term immediate threats (such as a lion) – not to an overflowing email inbox. When the brain detects threat, a region called the amygdala initiates the body’s classic fight-or-flight response. Stress hormones including adrenaline and cortisol are released. Heart rate increases, breathing quickens and attention sharpens. Energy is diverted away from long-term maintenance tasks towards immediate action. The modern world makes it worse Modern stressors are psychologically powerful but biologically peculiar. Unlike predators, they rarely resolve quickly. Emails continue arriving. Work follows us home through smartphones and laptops. Social media creates a constant stream of social comparison and low-level vigilance. Even leisure time has become strangely porous, interrupted by notifications, messages and often the expectation of permanent availability. The result is that the parts of the brain responsible for keeping us alert can remain partially activated for long periods. This matters because sleep is not simply the absence of wakefulness. Falling asleep requires the brain to actively reduce alertness. A network of arousal centres in the brainstem, hypothalamus and forebrain normally keeps us awake and attentive during the day. To transition into sleep, these systems must quieten down. Under long-term stress, however, the brain can become stuck in a state of hyperarousal. Even when the body is exhausted, the brain continues scanning, anticipating and rehearsing. From an evolutionary perspective, this makes a certain kind of sense. If the environment feels threatening or uncertain, being fully offline may not seem safe. In addition, artificial light suppresses melatonin, the hormone that helps regulate sleep timing. Smartphones provide endless cognitive stimulation at exactly the point the brain should be winding down. Doomscrolling combines emotional arousal, uncertainty and novelty – three things human attention systems find almost impossible to ignore. Then there is rumination: the repetitive mental replaying of worries and problems. Humans possess a remarkable ability to mentally simulate the future and revisit the past. This capacity helps us plan, learn and avoid danger. But it also means the brain can continue generating stress responses long after any immediate threat has disappeared. There is a way out. Consistent routines, reduced evening stimulation, exercise, daylight exposure and limiting late-night screen use can all help reinforce the signals that night is a time for recovery rather than alertness. 2) Good News!! The Earth will (probably) NOT be swallowed by the Sun In about 5 billion years, the Sun will run out of fuel, first expanding into a red giant and eventually becoming a white dwarf that will continue cooling for hundreds of billions of years. Will the Earth be pulled into the expanding red sun and disappear forever? Or, though long since rendered uninhabitable, will it continue orbiting the white dwarf remnant of the Sun until the universe reaches its eventual heat death? A red giant is a star that has exhausted the supply of hydrogen in its core and has begun thermonuclear fusion of hydrogen in a shell surrounding the core. They have radii tens to hundreds of times larger than that of the Sun. However, their outer envelope is lower in temperature, giving them a yellowish-orange hue. Over its main sequence life, the star slowly fuses the hydrogen in the core into helium; its first life ends when nearly all the hydrogen in the core has been fused. For the Sun, this lifetime is approximately 10 billion years. For the Sun and stars of less than about 2 M☉ the