Many of us have trouble falling asleep from time to time - usually because of stress or illness.
But when sleep problems become a regular occurrence and interfere with daily life, that’s a sign of a sleep disorder like insomnia and sleep apnea.
If left untreated, sleep disorders can increase the risk of accidents and debilitating conditions such as depression.
Sleep disorders are usually caused by factors that interrupt the sleep cycle - which is a period of sleep that lasts about 90 minutes, during which we move through five stages.
Over the course of the night, there are four or five sleep cycles.
The first four stages make up non-rapid eye movement or NREM sleep which is roughly 80% of the sleep cycle, while the fifth part is rapid eye movement or REM sleep, which accounts for the last 20% of the sleep cycle.
Across the four stages of NREM, we move from very light sleep during Stage 1, to very deep sleep in Stage 4.
During NREM there’s minimal muscle activity and our eyes don’t move much.
During REM sleep, the eyes dart around, and this is where dreaming occurs, memories are consolidated, and where we get the most rest.
The stages can be interrupted by various things. Heavy smoking, stress, and jet lag can make it hard to fall asleep, and substances like alcohol, caffeine, cocaine, and other stimulants can reduce NREM sleep.
The ability to fall asleep quickly also decreases with age, especially in those with medical conditions that cause dyspnea, pain, nocturia, or nausea.
Individuals end up feeling really tired during the day and are often unable to perform at work, at school, and can struggle to have a healthy sex life.
Often the fatigue can lead to irritability and difficulty focusing, and can worsen feelings of depression and anxiety.
Some individuals get into a vicious cycle where they drink a lot of coffee to stay awake, and that can worsen the underlying problem.
There are nine sleep-wake disorders according to DSM-5.
The most common is insomnia, and the other eight are primary hypersomnias, which include narcolepsy and hypersomnolence disorder, breathing-related sleep disorders, circadian rhythm sleep-wake disorders, parasomnias, restless legs syndrome, substance or medication-induced sleep disorder, and specified sleep-wake disorder, and unspecified sleep-wake disorder - diagnoses which are reserved for symptoms that don't fit any of the main sleep disorders.