Subtle signs of tiredness
SOME signs of exhaustion are easy to spot: dark circles under eyes, excessive yawning, and finding it difficult to wake up in the morning. But there are also some more subtle signs that the human body exhibits when it’s not getting enough rest.
1. Forgetfulness
Sleep is vital for the production of new memories and knowledge. Research shows that on average, people who sleep less than five hours a night are 25 per cent more forgetful than those who sleep longer. Deep slow wave sleep – which takes place during non-REM sleep – is associated with restoring memory.
2. Moodiness
People who sleep less than they need to are more likely to react negatively when things go badly. This is because lack of sleep leads to a rise in amygdala activity in the brain – which is part of the limbic system involved with creating emotions – and also causes a disconnect between it and other areas that regulate its function.
3. Hunger and weight gain
Sleep and appetite are closely linked. Ghrelin stimulates the appetite while leptin suppresses it, and these hormones regulate normal hunger levels. If we don’t get enough sleep, ghrelin and leptin levels are altered. Our bodies’ response to glucose and release insulin is also altered, putting us at risk of type 2 diabetes.
4. Impulsivity
Lack of sleep impairs cognition, attention and decision making, so it’s perhaps no surprise that it can also affect impulse control. Scientists who studied the behaviour of a group of sleep-deprived subjects found that no matter how hard the participants tried to make good choices, sleeplessness created a kind of short-circuit in their brains that stopped them from following through on these choices.
5. Illness
Bodies need sleep to fight infectious disease. During sleep, proteins called cytokines are produced by our immune systems and used to fight infection and inflammation or when we’re under stress. But if we don’t have enough sleep, we don’t produce enough of them to fight back. Prolonged lack of sleep is also linked to cardiovascular disease, high blood pressure, mental illness and other serious illnesses.