Dr Amir Khan, known for his appearances on ITV's Lorraine and Good Morning Britain, has outlined why some people may feel constantly exhausted despite getting enough sleep. In a TikTok video, the doctor explained the difference between being "busy tired" and "medically tired," and highlighted several common underlying causes.
Busy tired vs medically tired
"Are you feeling tired all the time? Well, you're not lazy," he said. "You're not just getting old. But there is a difference between being 'busy tired' and being 'medically tired', and knowing that difference can literally change your life."
He explained that tiredness from long days, late nights, stress, children or late-night television usually improves after a good night's sleep or a weekend of rest. However, constant exhaustion despite quality sleep, waking up feeling tired or foggy, difficulty concentrating, or relying on caffeine to get through the day could signal a medical issue.
Common medical causes
The first possible cause Dr Khan highlighted is anaemia, which occurs when there is a low red blood cell count. "Low iron is a common one. It means less oxygen is reaching your cells. You feel weak, dizzy and short of breath climbing stairs, for example," he said.
Another potential explanation is insufficient Vitamin D levels, which are mainly obtained from sunlight. Dr Khan said: "Low Vitamin D can leave you feeling constantly tired, achy and low in mood. It's really common, so make sure you're taking your Vitamin D supplement."
Thyroid issues can also cause persistent fatigue. "If your thyroid's underactive, everything slows down. Your energy, your mood, even your digestion," Dr Khan said.
Sleep apnoea, depression and other causes
Sleep apnoea, a condition where breathing stops during sleep, was next on his list. "You might be sleeping, but your oxygen levels drop overnight," he said. "You wake up unrefreshed and can't figure out why. Normally we see it with people who are overweight, snoring, and their partner says they hear them stop breathing and then start again during the night."
Depression and low mood can also cause daytime exhaustion. "Mental health fatigue is real. It's that heavy tiredness that doesn't shift even when life feels calm," Dr Khan explained.
He noted that more serious conditions, such as cancer, could be responsible, though such cases are uncommon. He advised anyone experiencing fatigue alongside unexplained weight loss, night sweats, or blood in the stool or urine to consult their GP without delay. Hormonal problems around the menopause can also contribute to tiredness.
Dr Khan advised: "So, if rest doesn't fix it, don't just push through it. Ask your GP perhaps for a blood test, check your iron, B12, thyroid, maybe even do a stool test. And check your sleep quality."
"You deserve energy that lasts longer than your morning coffee. So are you busy tired, or medically tired? If you're not sure, get it checked. Your body is trying to tell you something."
