Sleep is one of the foundations of good health and one of the golden rules most people swear by. The checklist usually includes essentials like clocking in the recommended 7-8 hours each night. But when sleep is compromised, the effects do not stay limited to just surface-level exhaustion. They extensively affect your mental health and major cognitive performance.
When you are not getting enough sleep, have you ever wondered what it does to your brain and cognitive performance? Lack of sleep is more than just morning grogginess. Its impact can be far-reaching.
To better understand the consequences of poor sleep on the brain, HT Lifestyle reached out to Mehezabin Dordi, clinical psychologist at Sir H N Reliance Foundation Hospital, Mumbai. She explained that sleep is indispensable for active neurological repair, playing a critical role in restoring cognitive function, regulating emotions and maintaining overall mental clarity. When sleep is compromised, the brain’s ability to process information itself takes a hit.
Sharing her clinical experience, “As a clinical psychologist working extensively with anxiety, depression, and stress-related disorders, I can confidently say this: poor sleep is one of the most underestimated disruptors of mental clarity and emotional balance.”
4 ways brain gets affected
The psychologist listed four key ways in which lack of sleep can affect the brain, disrupting emotional balance, cognitive functioning, and the body’s stress response.
1. Emotional regulation suffers:
- Amygdala (emotional alarm system) becomes more reactive when sleep-deprived.
- Becomes up to 60% more reactive, meaning more intense emotions like being irritable, anxious, and emotionally sensitive.
2. Prefrontal cortex efficiency drops:
- This part of the brain is responsible for decision-making, impulse control, and rational thinking.
- When sleep is compromised, struggles with focus, memory, judgment, and mental clarity increase.
3. Stress hormones rise:
- Poor sleep increases cortisol levels, keeping the body in a low-grade stress state.
- Over time, this contributes to anxiety, mood swings, and burnout.
4. Emotional memories get processed poorly:
- REM sleep helps to process emotional experiences.
- Without adequate REM, unresolved emotional residue builds up, leading to emotional overwhelm.
Why do people struggle to sleep these days?
The psychologist attributed this to several major lifestyle factors, whether it is excessive screen timebefore bed, where blue light delays melatonin production, or chronic stress caused by a high-pressure work culture that often leads to late-night overthinking. One important point she highlighted is that many people mistake mental fog or irritability as a part of their personality, when in reality it may simply be a sign of accumulated sleep debt.
Prevention
How do you ensure you are sleeping well? There are certain sleep behaviours you can adopt to improve sleep quality and reduce mental fog, stress, and irritability that often come with sleep deprivation. Here are some practical tips that Mehezabin shared:
1. Protect a consistent sleep window: Go to bed and wake up at the same time daily, even on weekends, brain loves rhythm.
2. Create a wind-down ritual: 30–45 minutes before bed, reduce stimulation. Dim lights. Avoid intense conversations. No work emails.
3. Limit blue light exposure: Stop screens at least 45–60 minutes before sleep. If unavoidable, use night mode.
4. Manage cognitive overactivity: Keep a ‘worry journal.’ Write down pending tasks before bed so the brain doesn’t rehearse them at 2 a.m.
5. Watch caffeine timing: Avoid caffeine 6–8 hours before bedtime.
6. Seek professional help if needed: Chronic insomnia often responds very well to Cognitive Behavioural Therapy for Insomnia (CBT-I), which has strong evidence support.
Note to readers: This article is for informational purposes only and not a substitute for professional medical advice. Always seek the advice of your doctor with any questions about a medical condition.
