You’re always hungry
If the brain is not getting the energy it needs from sleep it will often try to get it from food. Running low on rest can increase the production of ghrelin in your gut, which is also known as the hunger hormone, making you more likely to reach for the biscuit tin.
With an increased appetite comes another symptom of sleep deprivation: weight gain. A lack of sleep can have direct effects on your metabolism, it tends to slow down without proper rest. A 2012 study found that just four and a half hours of sleep for four days straight can reduce your fat cells’ ability to respond to insulin, the hormone responsible for regulating energy, by 30%.
Can’t remember what you did last night or where you put your car keys—again? Before you panic about having a serious memory problem, know that your brain is probably fine. When we are tired we are usually not paying enough attention to what’s going on so it becomes harder to make a memory.
Also, certain sleep stages are needed in order to improve memory, for example, factual memories are enhanced by slow wave, deep sleep so if you don’t get enough of this you may find your memory is suffering.
Your emotions are all over the place
Ever found yourself welling up over nothing when you’re tired? When we are sleep deprived we become over- reactive to stimuli so our emotions can feel out of control. Things that normally haven’t gotten us worked up in the past—a tear-jerker rom-com or stressful work deadline—may provoke anxiety, sadness, or anger. (It could also go the opposite way: you may find yourself feeling ‘giddy’ and laughing at anything!)
You are always poorly
If you don’t get enough sleep your immune system can really suffer. In particular, you might find that it’s harder to shake off a cold. A 2009 study followed the sleeping habits of 153 volunteers for 14 days straight. Researchers found that people who got less than seven hours of sleep were nearly three times as likely to develop a cold than those who got eight hours or more rest a night.
Your skin looks older
They call it “beauty sleep” for a reason. While you’re out for the count, your skin works to repair any damaged cells, so not getting enough rest can disrupt the process. A 2013 trial found that skin recovery was 30% higher in those who had good quality sleep over those with poor sleep. Not only can you expect more breakouts when you skip out on rest, your skin may also appear older.
You think you’ve fallen asleep at the wheel
When you nod off for a few seconds without even knowing, it’s called micro-sleep. The brain says, ‘I don’t care what you want to do, we are going to sleep,’. It’s your body’s way of forcing you to get the rest you need. The big problem is that micro-sleep can be extremely dangerous if you happen to be driving. Estimates show that 2.2% to 2.6% of total fatal crashes involved drowsy driving.