Why you still feel exhausted after 8 hours of sleep—what your mind and body are trying to tell you

You slept 7 hours. The magic number. You did everything right: You crashed at 10, and woke up at 5. 

And you’re still tired. You don’t want to move. It’s not just the regular sleepiness. just the thought of making your way through the day seems exhausting.

Maybe, another 9 hours will do.

And maybe, that won’t be enough either.

You aren’t alone in this exhaustion. It’s quite, unfortunately, common. And so, we turned to specialists like Dr Mohammad Nami, a clinical, cognitive neuroscientist and sleep health professional at the School of Health Sciences and Psychology, Canadian University, Dubai.

It’s a question that Dr Nami hears quite often, too: ‘I sleep seven or eight hours a night and feel fine the next next day, but I still feel tired, foggy and irritable. What’s wrong with me?’

As he explains, “The often-quoted ‘magic number’ for sleep is 7 to 8 hours. While this is generally true, amount of sleep isn't the full story, quality's every bit as paramount, if not more so.”

You need to think of it as eating three healthy meals a day, whether or not there is a surplus of food it does not matter, if your body isn’t taking up the nutrients. “And likewise, if your brain doesn’t pass through the stages of sleep it needs, in particular deep ‘slow-wave’ sleep and REM sleep, you may lose out on the restorative aspects of sleep,” he says.

So, why do you lose out on good sleep? Here are possible reasons: 

Obstructive Sleep Apnea (OSA)

You may unknowingly stop breathing during sleep, jolting awake repeatedly, often without realising it. This interferes with the deep stages of sleep your brain and body desperately need.

Chronic insomnia

Going to bed early isn’t enough if you struggle with frequent awakenings or lie awake in a hyper-aroused state. Even if it looks like you’re resting, your brain may still be on high alert.

Restless leg syndrome or periodic limb movement disorder

Nighttime twitching or leg discomfort can fragment your sleep without fully waking you, silently chipping away at rest quality. A 2021 study published in PLOS ONE, conducted among medical students found that RLS was significantly associated with poor sleep quality and insomnia symptoms.

Circadian rhythm misalignment

Even if you sleep ‘enough,’ it may not align with your body’s internal clock. For example, if you're a natural night owl forced to sleep from 10 PM to 5 AM, your sleep won’t be as efficient or restorative.

Mental fatigue versus physical fatigue

You feel worn out, but oddly restless. Your brain keeps prodding you for a break, while your body feels wired. According to Dr Nami, this split, mental versus physical exhaustion, can wreak havoc on your ability to rest. It’s a common disconnect, whether you’re a student pulling all-nighters, a professional chasing deadlines. It’s all the cognitive load. 

Here’s the neuroscience: Mental fatigue stems from high-frequency brain activity and depleted neurotransmitters like dopamine and serotonin. Physical fatigue, on the other hand, is more about muscle effort and energy expenditure. If you’ve been sedentary, your body might not be tired enough to let you fall asleep, even if your mind is screaming for rest.

The body’s verdict: Trouble falling asleep, staying asleep, and waking up feeling like you barely slept at all.

If you’re emotionally drained, your brain’s sleep circuits may be out of sync too.“Burnout, characterised by emotional exhaustion, depersonalisation, and reduced sense of achievement, can severely alter sleep patterns,” says Dr Nami.

Racing thoughts, nighttime over-planning, and a mind that simply refuses to power down. And this state, where your nervous system is low-key revved up, an sabotage your ability to fall and stay asleep.

Stress floods your system with cortisol, your primary stress hormone, particularly harmful when elevated at night. Cortisol can:

You might technically sleep the right number of hours, but you’ll still wake up groggy, anxious, and vulnerable if these deeper processes are interrupted.

You did everything right. You slept in the dark room, put away your screens and cleared your bed. But you’re still foggy, tired and moody.

Why? 

Possible causes: 

The goal isn’t just to clock hours, it’s to feel refreshed. Here’s how to turn good sleep hygiene into deep rest, explains Dr Nami.

Track your true sleep quality

Use a journal or sleep tracker to note sleep onset, night awakenings, and how refreshed you feel. If you suspect deeper issues, a sleep study can rule out apnea or movement disorders.

Re-sync your sleep-wake cycle

Expose yourself to morning light, maintain consistent bedtimes (yes, even on weekends), and limit screens before bed to preserve your circadian rhythm.

Keeping anxiety at bay

When your thoughts are on constant loop, it’s not just normal insomnia.  That’s where Cognitive Behavioral Therapy for Insomnia (CBT-I) comes in. It’s not just talk therapy for sleep. CBT-I is a science-backed method that helps reframe the thought loops and behavioral patterns that silently fuel your sleeplessness, like overthinking, or associating your bed with stress and rumination.

In fact, a 2022 study showed that CBT-I significantly improved both how fast people fell asleep and how well they slept overall, even among people who didn’t realise their anxiety was interfering with sleep.

Create a wind-down routine

Start a 30–45-minute ritual: Soft lighting, light reading, stretching, or journaling. Avoid doomscrolling or emotionally intense content before sleep.

Get moving 

Aim for 30–45 minutes of physical activity daily. Morning or early afternoon workouts are best for boosting neurotransmitters and improving deep sleep.

Nourish your brain and body

Eat a Mediterranean-style diet rich in omega-3s, magnesium, and tryptophan, found in oats, dairy, bananas. A 2024 meta-analysis published in Sleep Health pooled data from several observational studies and found something quite encouraging: people who followed a Mediterranean-style diet—rich in fruits, vegetables, whole grains, olive oil, fish, and nuts tended to fall asleep faster and sleep more soundly.

Specifically, the analysis showed better overall sleep quality and reduced sleep latency, which is how long it takes you to fall asleep after getting into bed). This likely has to do with the way this diet supports brain chemistry, lowers inflammation, and helps regulate hormones like serotonin and melatonin that are crucial for healthy sleep.

Final word:  Sleep isn’t just about quantity, it’s about the quality of rest and repair that happens behind the scenes. If you’re waking up after seven or eight hours feeling groggy, anxious, or deeply drained, you’re not imagining it. Knowing what happens during those hours, and what’s disrupting it, can help you reclaim your rest, and wake up not just well-slept, but truly restored.