Daytime Sleepiness: Why Do I Feel Sleepy In The Afternoon?

Feeling sleepy 30 minutes in the middle of the day is a common occurrence, often referred to as the midday slump. There are several factors that can contribute to this phenomenon, ranging from our body's natural circadian rhythm to lifestyle choices and underlying medical conditions. Understanding and addressing the root causes can help improve alertness and energy levels throughout the day.

Circadian rhythm

The circadian rhythm is the pattern your body follows based on a 24-hour day and is the name given to your body's internal clock. This rhythm tells your body when to sleep and when to wake up. It also affects several other body processes, like your hormones, digestion, and body temperature.

Your body sets your circadian rhythm naturally, guided by your brain. However, outside factors, such as light, can also affect the rhythm. When light enters your eye, cells send a message to your brain that it can stop producing melatonin (a hormone that helps you sleep).

These changes, driven by circadian rhythms, combine with sleep drive to cause a person to fall asleep at night. In the morning, as exposure to light increases, melatonin production stops and body temperature rises, promoting wakefulness.

If you don't sleep when your body tells you that it's time to—or if you sleep for long periods during the day—your circadian rhythms might become misaligned with the 24-hour cycle of day and night. This can have serious consequences for your health and well-being.

Sleep Problems

Misaligned circadian rhythms can make it harder to fall asleep at bedtime, lead to more wake-ups during the night, and result in less sleep overall. This misalignment can first be confused with insomnia, but frequent misalignment can, in fact, contribute to the development of insomnia.

Performance Issues

If your circadian rhythms are off, you are likely to experience a range of issues that affect your ability to function, such as excessive sleepiness, difficulty focusing, memory problems, and difficulty performing high-precision tasks.

Emotional and Social Difficulties

Sleep deprivation makes it harder to manage stress and regulate emotions, so if your circadian rhythms are out of sync, you're more likely to experience mental health struggles like depression and conflict in your relationships.

Accidents and Errors

Misaligned circadian rhythms increase your risk of having a car accident, making a serious mistake at work, or getting hurt on the job.

Health Problems

A range of health problems are associated with out-of-sync circadian rhythms, including obesity, diabetes, heart attacks, high blood pressure, and cancer.

Fatigue

Chronic misalignment of circadian rhythms or a lack of a routine to help entrain the internal clock can cause symptoms of low energy and grogginess.

Sleep disorders

One common sleep disorder is insomnia, which involves problems falling or staying asleep. About one-third of adults experience insomnia symptoms, and 4-22% meet the criteria for insomnia disorder. Insomnia is typically treated with a combination of sleep medications and behavioural techniques, such as cognitive behavioural therapy.

Another common sleep disorder is sleep apnea, a breathing disorder characterised by interruptions in breathing during sleep. This can cause snoring, snorting, gasping, or choking sounds, as well as daytime sleepiness and fatigue. Sleep apnea can be treated with lifestyle changes, such as weight loss or sleeping on one's side, and in some cases, a custom-fit plastic mouthpiece or a CPAP (continuous positive airway pressure) device may be prescribed.

Other sleep disorders include:

• Hypersomnia, which involves extreme daytime sleepiness despite adequate nighttime sleep.
• Restless leg syndrome (RLS), which involves a tingling or prickly sensation in the legs, along with a powerful urge to move them.
• Circadian rhythm disorders, which are problems with the sleep-wake cycle, making it difficult to sleep and wake at the right times.
• Parasomnia, which involves acting in unusual ways while falling asleep, sleeping, or waking from sleep, such as walking, talking, or eating.
• Narcolepsy, which involves extreme daytime sleepiness and sudden muscle weakness triggered by emotions.

If you are experiencing significant fatigue or an intense need to sleep during the day, it is important to consult a healthcare professional to determine the underlying cause and explore possible treatments.

Medical conditions

Feeling sleepy 30 minutes in the middle of the day could be due to a variety of medical conditions. Here are some possible reasons:

Sleep Disorders

Sleep disorders such as sleep apnea, insomnia, restless leg syndrome, and narcolepsy can cause excessive daytime sleepiness. Sleep apnea, for instance, involves repeated interruptions in breathing during sleep, leading to frequent awakenings and sleep fragmentation. This results in feeling sleepy during the day. Restless leg syndrome causes an uncontrollable urge to move the legs, making it challenging to fall and stay asleep. Narcolepsy, a rare sleep disorder, is characterised by involuntary napping, sleep paralysis, hallucinations, and muscle weakness during strong emotions.

Various medical conditions can disrupt sleep and cause daytime sleepiness. These include hypothyroidism, oesophageal reflux, nocturnal asthma, chronic pain, epilepsy, encephalitis, multiple sclerosis, Parkinson's disease, obesity, obstructive sleep apnea, delayed sleep phase syndrome, and genetic disorders. Additionally, mental health conditions like depression and anxiety can impact sleep. People experiencing depression often face low energy and fatigue, while anxiety can make it challenging to fall asleep due to a racing mind.

Medication Side Effects

Certain medications can cause drowsiness and excessive sleepiness as side effects. These include antihistamines, antiemetics (for nausea and vomiting), antidepressants, beta-blockers, benzodiazepines, muscle relaxants, and opioid painkillers. If you suspect your medication may be causing sleepiness, consult your doctor. They can advise on adjusting the dosage or exploring alternative treatments.

Idiopathic Hypersomnia

Idiopathic hypersomnia is a chronic sleep disorder characterised by constant excessive sleepiness despite adequate or extended periods of sleep. People with this condition may experience difficulty being awakened from sleep and often feel unrefreshed even after napping. The exact cause of idiopathic hypersomnia is unknown, but researchers are exploring potential links to neurotransmitters and genetic factors.

Lifestyle factors

There are many lifestyle factors that can contribute to feeling sleepy 30 minutes in the middle of the day. These include:

• Sleep deprivation: Not getting enough sleep or poor-quality sleep at night can lead to feeling sleepy during the day. This may be due to long working hours, family demands, or social life.
• Environmental factors: Broken sleep can be caused by a variety of environmental factors such as a snoring partner, a baby that wakes up during the night, noisy neighbours, temperature fluctuations, or an uncomfortable mattress.
• Shift work: Working night shifts or irregular hours can disrupt the body's internal clock (circadian rhythm), making it difficult to get restful sleep.
• Mental health: Mental states such as anxiety and depression can impact sleep. Anxiety can keep you awake at night, leading to sleepiness during the day, while depression can sap your energy and make it hard to fall asleep.
• Substance use: Alcohol, caffeine, and certain medications can disrupt sleep patterns and contribute to daytime sleepiness. This includes sedating medications, anti-hypertensive drugs, anti-epileptic drugs, and antihistamines.
• Diet: Eating a large lunch high in carbohydrates or fat can contribute to the afternoon slump. A heavy meal can make you feel sluggish, especially when coupled with your body's natural dip in energy after lunch.
• Lack of exercise: Not getting enough physical activity can lead to low energy levels and contribute to daytime sleepiness.
• Stress: Chronic stress can lead to fatigue and disrupt sleep patterns, further exacerbating feelings of sleepiness during the day.

If you are experiencing persistent or excessive daytime sleepiness, it is important to consult with a healthcare professional to rule out any underlying medical conditions and to discuss potential lifestyle changes that could improve your sleep quality.

Medication

Prescribed Medication

Many prescription medications can cause drowsiness as a side effect. These include:

• Antidepressants, particularly tricyclics such as amitriptyline, doxepin, imipramine, and trimipramine
• Antipsychotics, including clozapine, olanzapine, perphenazine, quetiapine, risperidone, and ziprasidone
• Anticonvulsants and anti-anxiety medications, such as benzodiazepines (alprazolam, clonazepam, diazepam, and lorazepam)
• Antihistamines, found in sleep aids and allergy medications
• Antiemetics, which are used to control nausea and vomiting
• Drugs to treat high blood pressure, including alpha and beta-blockers
• Opioids and other prescription pain medications
• Muscle relaxants
• Drugs for Parkinson's disease
• Medications for cancer treatment, including chemotherapy, immunotherapy, and radiation therapy
• Proton pump inhibitors (PPIs)

Over-the-Counter Medication

Over-the-counter medications can also cause drowsiness. These include:

• Sleeping pills, including natural supplements like melatonin and valerian
• Allergy medications (antihistamines) such as brompheniramine, diphenhydramine, hydroxyzine, and meclizine
• Gut medications, such as drugs that control nausea, vomiting, or diarrhea
• High cholesterol medications, including statins and fibrates

Lifestyle Adjustments

If you are experiencing daytime sleepiness due to medication, there are some lifestyle adjustments you can make to help manage this:

• Consult your doctor or pharmacist to see if there are alternative medications or versions of the drug that do not cause drowsiness
• Adjust the dosage or timing of your medication, but always do this under medical supervision
• Practice good sleep hygiene, such as maintaining a regular sleep schedule and avoiding naps during the day
• Avoid substances that can cause tiredness, such as alcohol, and limit your intake of caffeine and nicotine
• Exercise regularly, maintain a healthy weight, and eat a well-balanced diet
• Make your bedroom comfortable and relaxing, and ensure your environment is free from disturbances

Frequently asked questions