Insomnia is a word that is tossed about rather carelessly sometimes. Sleeplessness is not always insomnia. There are some basic differences between insomnia and sleep deprivation.
New parents, for example, usually suffer from sleep deprivation. Newborn babies tend to keep their parents up at night and/or wake them at frequent intervals. The parents are sleep deprived. They do not have insomnia.
Likewise, people who work shift work schedules and work a rotation of days, evenings, and nights are very likely to suffer from sleep deprivation rather than insomnia, even though they have the opportunity to sleep when they aren’t working. Their natural chemically regulated internal clocks are disrupted, and even though they have the opportunity to sleep in the daytime, still they do not sleep. But they don’t have insomnia. They are suffering from sleep deprivation.
Those who suffer from real insomnia are not likely to nap in the daytime. They don’t function well, but they don’t fall asleep either. On the other hand, those who are sleep deprived will fall asleep easily. They will nap. They may function during their working hours but not very well.
Sleep deprivation is the cause of more automobile accidents than you can even imagine. Teenagers are especially vulnerable to falling asleep while driving when they are suffering from sleep deprivation, although they are certainly not the only group affected. Shift workers often fall asleep on their way to or from their jobs. New parents are known to fall asleep at the drop of a hat. Those who are suffering from sleep deprivation are very likely to fall asleep at the most inopportune times, but those who suffer from real insomnia are not.
Those who suffer from any of the forms of insomnia simply find it difficult to fall asleep at any time of the day or the night.