According to the World Health Organization, hunger and malnutrition are the single gravest threats to the worlds public health and malnutrition is by far the biggest contributor to child mortality, present in half of all cases.Almost 90% of maternal deaths during childbirth occur in Asia and sub-Saharan Africa, compared to less than 1% in the developed world. Those who live in poverty have also been shown to have a far greater likelihood of having or incurring a disability within their lifetime. Infectious diseases such as malaria and tuberculosis can perpetuate poverty by diverting health and economic resources from investment and productivity; malaria decreases GDP growth by up to 1.3% in some developing nations and AIDS decreases African growth by 0.3–1.5% annually.Studies have shown that poverty impedes cognitive function although some of these findings could not be replicated in follow-up studies. One hypothesised mechanism is that financial worries put a severe burden on ones mental resources so that they are no longer fully available for solving complicated problems. The reduced capability for problem solving can lead to suboptimal decisions and further perpetuate poverty. Many other pathways from poverty to compromised cognitive capacities have been noted, from poor nutrition and environmental toxins to the effects of stress on parenting behavior, all of which lead to suboptimal psychological development. Neuroscientists have documented the impact of poverty on brain structure and function throughout the lifespan.Infectious diseases continue to blight the lives of the poor across the world.
Other causes include:
Anxiety
Brain tumor
Chronic pains
Concussion – a mild traumatic brain injury
Diabetes
Fibromyalgia
Head injury
Hypercalcemia – too much calcium in the blood
Hypermagnesemia
Hyponatremia – low blood sodium
Hypothyroidism – the body doesnt produce enough hormones that control how cells use energy
Meningitis
Mood disorders – depression
Multiple sclerosis
Narcolepsy – disorder of the nervous system
Skull fractures
Sleeping sickness – caused by a specific parasite
Stress

Medicine
Analgesics – mostly prescribed or illicit opiates such as OxyContin or heroin
Anticonvulsants / antiepileptics – such as phenytoin (Dilantin), carbamazepine (Tegretol), Lyrica (Pregabalin) and Gabapentin
Antidepressants – for instance, sedating tricyclic antidepressants and mirtazapine. Somnolence is less common with SSRIs and SNRIs as well as MAOIs. Antihistamines – for instance, diphenhydramine (Benadryl, Nytol) and doxylamine (Unisom-2)
Antipsychotics – for example, Lurasidone (Latuda), thioridazine, quetiapine (Seroquel), olanzapine (Zyprexa), risperidone and ziprasidone (Geodon) but not haloperidol
Dopamine agonists used in the treatment of Parkinsons disease – e.g. pergolide, ropinirole and pramipexole. HIV medications – such as efavirenz
Hypertension medications – such as amlodipine
Hypnotics, or soporific drugs, commonly known as sleeping pills. Tranquilizers – such as zopiclone (Zimovane), or the benzodiazepines such as diazepam (Valium) or nitrazepam (Mogadon) and the barbiturates, such as amobarbital (Amytal) or secobarbital (Seconal)
Other agents impacting the central nervous system in sufficient or toxic doses

Assessment
Quantifying sleepiness requires a careful assessment. The diagnosis depends on two factors, namely chronicity and reversibility. Chronicity signifies that the patient, unlike healthy people, experiences persistent sleepiness, which does not pass. Reversibility stands for the fact that even if the individual goes to sleep, the sleepiness may not be completely gone after waking up.