Health & Science
It is a myth that it is dangerous to wake up a sleepwalker because it may cause them a heart attack, shock, brain damage, or something else. It is not a myth that it is dangerous to wake up a sleepwalker because of the possible injury the sleepwalker may inflict upon themselves or the person waking them up.
Although the actual atmospheric lapse rate varies, under normal atmospheric conditions the average atmospheric lapse rate results in a temperature decrease of 6.4C°/km (3.5F°/1,000 ft) of altitude above ground level. The measurable lapse rate is affected by the moisture content of the air (humidity).
Sunburn can occur in less than 15 minutes, and in seconds when exposed to non-shielded welding arcs or other sources of intense ultraviolet light. Nevertheless, the inflicted harm is often not immediately obvious. After the exposure, skin may turn red in as little as 30 minutes but most often takes 2 to 6 hours.
Cutting onions irritates the lachrymal glands, causing them to excrete tears. Chewing gum while cutting onions prevents tears by forcing you to breathe through your mouth. This disperses the irritant so that a significantly smaller amount reaches the lachrymal glands, preventing them from being irritated enough to release tears.