When we don't get enough sleep our brains don't recharge enough.
Then we don't think as clearly as we do when refreshed.
Humans have a natural sleep drive which builds throughout the day whilst we remain awake. This grows into the evening until we eventually feel an overwhelming 'pressure' to sleep. Sleep pressure is then relieved as we sleep, until we wake up and the process starts once again.
Insufficient sleep, however, has been found to exacerbate the symptoms of several sleep disorders. Sleep paralysis and sleepwalking, for example, are more likely to occur after several nights of poor sleep or irregular sleep-wake schedules.
Symptoms of sleep deprivation
Lack of sleep symptoms tend to vary according to how long and how often we are sleep deprived within a certain period of time. In general though, it is fair to say that sleep deprivation affects us on physical, mental and emotional levels.
Experimental studies with healthy good sleepers, where total sleep time is restricted, indicate that lack of sleep (or certain stages of sleep), negatively impacts a huge range of functions, including emotional processing, pain thresholds, immune functioning and glucose metabolism.
Physical symptoms
Physically, lack of sleep may leave us struggling with low energy levels during the day. Findings from the Great British Sleep Survey show that poor sleepers are twice as likely to feel fatigued. In fact, 88% of poor sleepers struggled with reduced energy compared to only 29% of 'good' sleepers.
Sleepiness, as opposed to 'tiredness', is another physical symptom, demonstrated by our propensity to fall asleep or trouble to stay awake during the day.
Although not terribly common, lightheadedness can also be a consequence of sleep deprivation. Often, headaches and tension are found to increase after poor sleep; occasionally this may be accompanied by feelings of dizziness and light-headedness. It is recommended that you consult your doctor if you experience symptoms such as this.