- Fainting (vasovagal syncope)
Before fainting, you might feel lightheaded, warm, nausea, a cold sweat, or have tunnel vision.
- Sleep apnea
People with sleep apnea stop and restart breathing multiple times while sleeping.
- Medication reaction or side-effect
Medication side effects include nausea, vomiting, stomach upset, weakness, dizziness, seizures, and more.
- Narcolepsy
Narcolepsy is a brain disorder that makes people abnormally sleepy at times during the day.
- Heart rhythm disorder
Some heart rhythm disorders can cause a fluttering in the chest, shortness of breath, chest pain or dizziness.
- Sleep deprivation
Sleep deprivation occurs when the lack of restful sleep is severe enough to compromise basic body functions.
- Caffeine withdrawal
If you suddenly stop drinking caffeine, you get withdrawal symptoms, such as headache, fatigue, and bad mood.
- Dehydration (Children)
Dehydration, or not getting enough fluid, causes dry and sticky mouth, tearless crying, and more in children.
- Tetralogy of Fallot
Tetralogy of Fallot is a combination of heart defects causing bluish skin, trouble breathing, and more.
- Heat exhaustion
Heat exhaustion causes intense thirst, heavy sweating, pale, cool, and moist skin, muscle cramps, and more.
- Low blood pressure (hypotension)
Low blood pressure, or hypotension, can make you feel lightheaded and dizzy
- Atrial flutter
Atrial flutter is an abnormality of the heart's rhythm that causes rapid and sometimes irregular heartbeats.
- Dehydration (Adult)
Dehydration, or not getting enough fluid, causes low blood pressure, weakness, dizziness, fatigue, and nausea.
- Atrial fibrillation
Atrial fibrillation is a heart condition that causes heart palpitations, confusion, dizziness and more.
- Attention deficit hyperactivity disorder (ADHD)
Attention deficit hyperactivity disorder (ADHD) makes it hard to concentrate and focus.
- Insomnia
Insomnia symptoms include trouble staying asleep at night, feeling tired during the day, moodiness, and more.
- Restless legs syndrome
Restless leg syndrome causes intense discomfort in your legs and an overpowering urge to move them.
- Supraventricular tachycardia
Supraventricular tachycardia is fast heart rhythm starting in one of the upper chambers of the heart.
- Ventricular septal defect
A ventricular septal defect is a hole in the heart that some babies are born with
- Anemia
Anemia, a lack of red blood cells, can cause fatigue, pale skin, weakness, dizziness, headache and more.
- Lyme disease
Lyme disease is a bacterial infection spread through tick bites; symptoms include rash, fever chills, and more.
- Pulmonary embolism
A pulmonary embolism, a blood clot lodged in the lung, causes shortness of breath, chest pain, and more.
- Pulmonary hypertension
Pulmonary hypertension can cause shortness of breath, a fast heart rate, or lightheadedness.
- Drug overdose
A drug overdose can be fatal and causes sleepiness, confusion, coma, vomiting, and other symptoms.
- Hyperventilation
Hyperventilation is rapid or shallow breathing usually caused by stress or anxiety.
- Low blood sugar (hypoglycemia)
Low blood sugar, or low glucose levels, causes shakiness, anxiety, clammy skin, irritability, hunger, and more.
- Aortic regurgitation
Aortic regurgitation, when the aortic valve doesn't close completely, can cause severe heart symptoms.
- Dementia with Lewy bodies
Dementia with Lewy bodies is a brain disorder that causes problems managing memory and movement.
- Cocaine withdrawal
Cocaine withdrawal may cause feelings ranging from anxiety, irritability and sleepiness to suicidal thoughts.
- Amphetamine withdrawal
The symptoms of amphetamine withdrawal include depression, fatigue, increased appetite, and sleep problems.
- Aortic stenosis
Aortic stenosis is a condition of the heart causing shortness of breath, dizziness, or chest pain.
- Brain aneurysm
A brain aneurysm is a weak spot in a blood vessel in the brain that balloons and fills with blood.
