Health Check: why can you feel groggy days after an operation?

You have a small operation under general anaesthesia and go home the same day. Two days later you’re back at work, but you can’t concentrate and have a desperate desire to take a nap. Why does this happen and how can you prevent it?

General anaesthesia is a reversible drug-induced coma, during which you are unconscious, don’t feel pain and don’t remember anything. This is precisely what you want when you’re having an invasive or painful procedure.

However, some people suffer lingering effects in the days after anaesthesia. These include drowsiness, slowed reaction times, and difficulty concentrating, remembering new information and finishing complex tasks.

Thankfully, these unwanted effects usually wear off by the next day, but sometimes they last for a few more days or even weeks. Then they can really disrupt your ability to work or get anything done at home.

It’s easy to blame the anaesthetics

The effects of general anaesthesia may appear to linger for days after surgery for many reasons. Tiredness after a procedure is commonly attributed to anaesthetics. But modern anaesthetics wear off completely in a couple of hours, so the real picture is usually more complicated.

The surgical condition for which you had the procedure may have stopped you leading a full and active life for some time, resulting in lack of fitness and less reserve for recovery.

The surgery itself causes tissue injury. After surgery, your body undergoes repair and recovery, which drives a higher baseline metabolic rate and draws on your nutrient stores. So it isn’t surprising such intense activity at a cellular level results in feeling tired after surgery.

If you ignored your doctor’s advice to take it easy before or after surgery, that could also explain why you’re feeling tired.

Then there’s pain treatment before and after the procedure, which can also contribute to grogginess.

For instance, opioids (such as oxycodone) and gabapentinoids (such as pregabalin) are strong pain medicines often prescribed after surgery. They are important in ensuring a comfortable recovery and rapid return to normal life, but may result in grogginess and confusion, especially in higher doses.

Opioids are usually needed for only a few days after surgery and these side effects stop when you stop taking them.

Finally, general anaesthetics interfere with your body clock. This could be because anaesthetics interfere with brain hormones, such as melatonin, and messenger chemicals called neurotransmitters.

While melatonin tablets can treat jet lag, which is also a disruption of the body clock, there is no good evidence to use melatonin for anaesthesia-induced body-clock disruption in humans.

Can you prevent grogginess?

An operation is a major life event. Make sure you get adequate rest and have enough support at work and home before your surgery.

A bit of anxiety is normal before surgery and can also be exhausting. You can reduce your anxiety by asking for clear explanations of what to expect, and by maintaining a warm, comfortable and calm waiting environment.

If you are very anxious, your anaesthetist can give you a sedative “pre-med” before you go to theatre. But the use of sedatives is a balancing act, as the calming effect before the procedure is desirable but not the “hangover” drowsiness afterwards, which may last for several hours.

Your anaesthetist is the medically trained specialist who can not only give you a “pre-med” but will look after you during your operation and plan your recovery. He or she will develop an individualised anaesthetic plan based on short-acting anaesthetics and a combination of pain-killings drugs.

Your anaesthetist will also advise you how to best control your pain after surgery and when you return home. This will often involve using simple pain medicines, such as paracetamol and anti-inflammatory drugs, as well as opioids, which you will need to treat strong pain. Using simple pain medicines will help to reduce the doses of opioids that you need, and help you to avoid the nausea, constipation and grogginess that goes with them.

Get back into good sleep habits

After a procedure, you can combat the disruption to your body clock by practising good “sleep hygiene”. This involves maximising cues to the body that it is time to sleep in the evening. These could include avoiding stimulants like caffeine and alcohol, going to bed at a similar time each night, being in a dimly lit room and engaging in calming or restful activities before sleep, like reading.

Making sure you are exposed to bright sunshine during the day and avoiding back-lit screens on technology devices in the evening can also help.

Lingering grogginess after general anaesthesia is hardly ever sinister. But if it is persistent, getting worse rather than better, or is associated with confusion, weakness or numbness, then you must see your doctor.

The authors do not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and have disclosed no relevant affiliations beyond the academic appointment above.