Why Can’t I Sleep All of a Sudden? Six Possible Causes

Q: How long does short-term insomnia usually last?

Short-term (acute) insomnia typically lasts from a few nights up to a few weeks. It is often triggered by stress, illness, travel, work pressures, or sudden changes in routine, and usually improves once the underlying cause settles and sleep habits stabilise.

Q: Can stress alone really keep someone awake all night?

Yes. Stress activates the body’s fight-or-flight response and can keep arousal and cortisol higher than normal. This makes it harder for the brain to switch into sleep, leading to difficulty falling asleep, lighter sleep, or frequent awakenings.

Q: Is it better to stay in bed or get up when unable to sleep?

If sleep has not come after around 20 to 30 minutes, getting out of bed and doing something calm in low light is often more effective than lying awake. This helps prevent the brain from associating the bed with wakefulness and frustration.

Q: Do naps make insomnia worse?

They often can. Naps reduce sleep pressure, which can make it harder to fall asleep at night. This effect is more noticeable when insomnia is already present, especially if naps are long or taken late in the day.

Q: Does alcohol help with falling asleep?

Alcohol may feel sedating at first, but it commonly disrupts sleep later in the night. It can reduce restorative sleep and increase awakenings, which often leads to poorer sleep quality and next-day fatigue.

Q: Are sleeping pills necessary for short-term insomnia?

In most cases, no. Short-term insomnia often improves once triggers such as stress, irregular schedules, caffeine, alcohol, or an unhelpful sleep environment are addressed. Medication may be appropriate in some situations, but behavioural changes are usually the first-line approach.

Q: Can insomnia become chronic if ignored?

Yes. Repeated nights of poor sleep can create a learned pattern where bedtime becomes associated with worry and alertness. Addressing the causes early, and avoiding habits that worsen sleep (such as long naps and irregular wake times), reduces the risk of insomnia becoming persistent.

James Smurthwaite
Jan 30
7 min read

Short-term insomnia can be frustrating, maddening and – if you’ve never experienced it before – extremely confusing. ‘Why am I still awake at 3am?’ ‘Why won’t my brain switch off?’ Will counting sheep really do the trick?’ These are all questions sufferers ask themselves in the small hours, especially those who’ve never had any need to stock sleeping pills or over-the-counter supplements.

The reasons for this unwelcome condition are wide and varied but, by speaking to experts in the field, we’ve compiled a list of the most common causes.

Woman sleeping peacefully in a sunlit room, wrapped in white sheets. Brown curtains and soft light create a serene, cozy atmosphere.

1: You’re Not Exercising Enough

We all know regular workouts help us tone our bodies and shed excess weight. But the advantages don’t end there.

Preeya Fozdar, an Internal Medicine physician at the Twin Hills Primary Care practice in Pittsburgh, USA, says it could be one of the easiest fixes for short-term insomnia:

“If your body is tired, your mind will follow. Exercise has a multitude of benefits, so I do recommend a high intensity session daily, but even low-intensity activity, such as walking, shows sleep benefits. If you're not sure about an activity or timing, run your own experiment. Try something for a week and compare your wearable device info from one week to the next!”

2. You’re Stressed Out

Cortisol, a key stress hormone, has a significant impact on our sleep. The level fluctuates in our bodies throughout the day, often spiking whenever we become tense, worried or anxious. Unfortunately, those spikes can continue up until bedtime, disrupting the brain’s ability to switch off.

Samia Estrada, a US-based clinical psychologist focusing on health and happiness recommends various steps to push cortisone levels down to zero.

“Relaxation techniques, meditation, mindfulness, and guided imagery are great ways to reduce the stress level in our body. Practicing them prior to bedtime helps to relax the body enough to fall asleep and stay asleep.

“Other helpful tactics for lowering stress are gratitude (i.e. remembering three good things that happened in your day), having a warm or hot shower prior to bed and avoiding the consumption of arousing media, such as news or shows that have you on the edge of your seat. Save these for earlier in the day.”

Dr Jennifer Barbera, a Canadian psychiatrist helping those who struggle with anxiety and low mood recommends another method of managing nighttime stress.

“Hyper-arousal can interfere with sleep, so you need to reduce arousal in the nervous system. An important strategy to consider for this Is to have a notepad near the bed where you jot down worries or concerns so that you can focus on leaving them there until the next day when you can actually do more to address them.”

3. You’re Eating (And Drinking) Wrongly

Close-up of a charcuterie board with prosciutto, cheese, and arugula, accompanied by a wine glass. Warm, dimly lit restaurant setting. — Heavy meals and wine do not make for good sleep

For many of us a ‘nightcap’ is a just reward at the end of a long and tiring day – and exactly what we need to help us relax and unwind. Sadly, that glass of wine or shot of your favourite spirit could have the opposite effect.

“Most people believe alcohol helps them sleep,” says Dr Estrada. “but what they don't realize is that alcohol affects your restorative sleep, so even if you were able to fall asleep quickly and sleep enough hours, you may not feel well rested when you wake up. Even worse, you may have frequent wake ups.”

And alcohol isn’t the only ‘liquid enemy’ of a good night’s rest. “It’s best to limit the use of caffeinated products to the morning only,” says Dr Cooper Stone, a Philadelphia-based psychiatrist “whether that’s tea, energy drinks, many sodas, or even certain chocolates. Not only will the caffeine keep you up, but the diuretic effect may also cause you to have to use the bathroom one or more times in the middle of the night.”

Dr Stone also has a word of warning about food.

“If you go to sleep with an empty stomach and you find that your stomach grumbles and is distracting, go ahead and eat a light snack – with emphasis on ‘light!’. However, you should avoid eating heavy meals before bed that can make it more difficult to fall asleep and can cause uncomfortable acid reflux.”

4. You’re Napping Too Much

A sleepless night can set off a vicious cycle, with sufferers taking to the sofa during the day in an effort to catch up on their ‘lost hours’. Bad move, according to Dr Stone.

“One of the most effective things I’ve found in my patients is to avoid napping during the day, as hard as that may be, especially if you’ve been having a poor night sleep as of late. As tempting as it may be to snooze a little bit, resist the urge! It’ll make falling asleep at night that much easier.

“It’s also important to be regular about your sleep schedule. In other words, wake up at the same time every day, and go to sleep at the same time every day. This will help keep your rhythm regular.”

5. You Need a Night-Time Routine

Person in red pants using a smartphone app on a bed, checking “Foods to eat” list. A cardboard box with “Nulos” text lies nearby. — Try to avoid screentime right before bed

A majority of the experts we spoke to stressed the importance of ‘sleep hygiene’ – a term that refers to a set of habits and environmental practices that promote consistent, high-quality sleep by aligning with your body's natural circadian rhythm. Good sleep hygiene includes retiring at the same time each night, avoiding screens and heavy meals before sleep, ensuring the bedroom is dark, quiet and cool (ideally 15-19°C, or 60-67°F), and that the bed itself is reserved strictly for sleep or intimacy, not work or TV.

Sleep hygiene is just one element of Cognitive Behavioural Therapy for Insomnia (or CBT-I) , as practised by Dr Shmaya Krinsky, founder of Anxiety and Behavioural Health Psychotherapy in the USA. As well as a consistent sleep schedule and a reduction or elimination of naps his programme includes the following components, which can all be tried at home:

Stimulus Control: Associating the bed with sleep and sex only. If unable to sleep, getting out of bed and doing something relaxing until sleepy.

Sleep Restriction: Limiting the time spent in bed to the actual amount of time spent sleeping to increase sleep efficiency.

Cognitive Restructuring: Identifying and changing negative thoughts and beliefs about sleep that contribute to insomnia.

Relaxation Techniques: Practices such as progressive muscle relaxation, deep breathing exercises, and mindfulness meditation to help reduce anxiety and promote relaxation.

6. You’re ignoring the little clues

What causes sleeplessness is often easily identifiable. You may have suffered a bereavement, experienced a job-loss or fallen ill – all of which can cause tension and anxiety. But the triggers can also be more subtle.

“Consider other health changes or medications,” advises Dr. Fozdar. “Are your allergies disrupting your sleep? Any new medications? Also consider dynamic changes in your sleep environment: Is your partner having issues too? What about your pets? Sometimes, once the underlying issue is addressed, the sleep takes care of itself.”

According to Dr Estrada, your immediate surroundings could be at the root of the problem:

“Be mindful of your environment: we don't always recognize that it could be playing a big part on our sleep. Sleeping with a partner can be great - until that partner starts snoring, or lays in the bed like a starfish, leaving you only with a few inches of mattress to sleep on.

“Have you ever tried to sleep while the neighbours are partying in the back yard? Perhaps a white noise machine or earplugs would be helpful. Noise can play a big role in our sleep, and so can temperature. Our body temperature drops as we fall asleep, so if we are in a very hot room or cuddled under too many blankets, we may actually be doing a disservice to our sleep.”

Short-term insomnia rarely appears out of nowhere. In most cases, it is usually the result of small, overlapping pressures that keep the brain in a state of alertness when it should be winding down. Stress, disrupted routines, caffeine, alcohol, late meals, screens, noise or temperature can all interfere with sleep, and when several are present at once, even good sleepers can struggle.

The good news is that short-term insomnia is often reversible. Once the main triggers are identified and corrected, sleep usually returns without medication. Regular exercise, consistent bedtimes, calmer evenings and a sleep-friendly bedroom give the nervous system the signal it needs to switch off. If problems persist, evidence-based approaches like CBT-I can help, but for most people, sleep improves as soon as the underlying causes are addressed.

Frequently Asked Questions: Why Can’t I Sleep All of a Sudden?

How long does short-term insomnia usually last?

Short-term, or acute, insomnia typically lasts anywhere from a few nights to a few weeks. It is often triggered by stress, illness, travel, work pressures or sudden changes in routine. In most cases, sleep returns once the underlying cause settles and normal habits are restored.

Can stress alone really keep someone awake all night?

Yes. Stress activates the body’s fight-or-flight system and raises cortisol levels, which directly blocks the brain’s ability to enter sleep. Even when the body feels tired, a stressed nervous system remains alert, leading to racing thoughts, shallow sleep or repeated awakenings.

Is it better to stay in bed or get up when unable to sleep?

If sleep does not come after about 20 to 30 minutes, getting out of bed and doing something calm in low light is usually more effective than lying there frustrated. This helps prevent the brain from associating the bed with wakefulness and anxiety.

Do naps make insomnia worse?

They often do. Napping reduces sleep pressure, which makes it harder to fall asleep at night. Even short daytime naps can weaken the body’s natural drive for nighttime sleep, especially when insomnia is already present.

Does alcohol help with falling asleep?

Alcohol may make people feel drowsy, but it disrupts deep and REM sleep and increases night-time awakenings. This leads to lighter, less restorative sleep and can make insomnia worse over time.

When should insomnia become a medical concern?

If poor sleep lasts longer than three to four weeks, or starts affecting mood, concentration, work or physical health, it is worth seeking medical advice. Persistent insomnia can often be treated very effectively with structured therapies such as CBT-I.

Are sleeping pills necessary for short-term insomnia?

In most cases, no. Short-term insomnia usually improves once triggers like stress, poor routines or environmental problems are addressed. Medication may be used in some situations, but behavioural and lifestyle changes remain the first-line treatment.

Can insomnia become chronic if ignored?

Yes. Repeated poor sleep can train the brain to associate bedtime with frustration and alertness, allowing short-term insomnia to turn into a longer-term pattern. Addressing sleep problems early makes recovery much easier.