Sleep and Circadian Rhythms - Continued

Physiological Effects:

• Hormonal Disruption: SCRD impacts the stress axis, reproductive hormones, appetite regulators (leptin and ghrelin), and even growth hormone.

• Immune System Dysregulation: Poor sleep weakens the immune response, leaving us more vulnerable to illness.

• Toxin Clearance: Sleep is when our brains clear waste via the glymphatic system. Without it, beta-amyloid proteins – linked to Alzheimer's – accumulate more rapidly.

• Cancer Risk: One of the most alarming revelations was that night shift work has been classified by the World Health Organization as a Group 2A carcinogen – meaning it is "probably carcinogenic to humans." Foster highlighted studies linking long-term night shift work to increased rates of breast, colorectal, and prostate cancer.

Psychological & Cognitive Effects:

• Mood Instability: Just a few nights of poor sleep can result in irritability, increased anxiety, and emotional volatility.

• Paranoia and Delusions: A compelling study Professor Foster cited involved healthy adults whose sleep was restricted. After just a week, they began showing signs of paranoia and even mild delusional thinking. These weren’t individuals with mental illness – they were simply sleep-deprived.

• Cognitive Decline: Memory, attention, decision-making and multitasking ability all drop significantly. We become reactive, rather than reflective.

Societal Costs:

• Accidents and Errors: Perhaps most chillingly, Foster referenced a study showing that night shift workers are over 30% more likely to be involved in a serious car accident when driving home after a shift. The effects of sleep deprivation are comparable to alcohol intoxication in terms of impaired reaction times.

Contributing Factors

Unfortunately, the majority of individuals suffering from mental health problems also experience some form of clinically significant sleep disruption and it's linked to a number of other health complaints too.

Some of the known factors contributing to sleep difficulties include:

• Sensory Sensitivities: Heightened sensitivity to sound, light, smells, and textures, which interfere with the ability to relax and fall asleep.

• Social Cueing: Difficulty understanding social cues related to bedtime – daytime activities vs night-time sleep.

• Medical Conditions: Sleep apnoea, epilepsy, or gastrointestinal issues, can increase SCRD.

• Medications: Drugs used to treat conditions like ADHD or mood disorders may promote SCRD (methylphenidate [MPH] & amphetamine formulations).

• Increased Anxiety: Problems falling asleep and staying asleep.

• Delayed Circadian Rhythm: Sleep times shifted later.

The Vicious Cycle: How Poor Sleep Creates More Poor Sleep

The consequences of SCRD often lead to stress, low mood, unhealthy coping mechanisms (like caffeine to stay alert and alcohol to unwind), and a feedback loop that makes good sleep even harder to achieve. This cycle can fuel the development or worsening of chronic conditions like anxiety, depression, and metabolic disorders.

What Can We Do About It? Professor Foster’s Advice

Thankfully, the talk wasn’t all doom and gloom. Professor Foster offered a range of evidence-backed strategies to support healthier sleep and circadian rhythms:

1. Prioritise Light Exposure

• Get outside in natural light within 30 minutes of waking up. Light is the primary cue that sets your circadian clock.

• Dim your lights in the evening. Avoid screens for at least an hour before bed to support melatonin release.

2. Anchor Your Sleep

• Set a regular wake-up time – even on weekends.

• Aim for consistency more than perfection. One late night won’t undo everything, but chronic irregularity will.

• If you’re travelling or recovering from poor sleep, shift your wake time in small 15-minute increments to gently reset.

3. Create a Sleep-Friendly Environment (My Favourite Section)

• Cool, dark, and quiet rooms promote the best sleep.

• Consider blackout blinds and white noise if light and sound pollution are issues.

• Pay attention to scent: Prof. Foster pointed out that the smell of the room can affect your ability to fall asleep. Opt for fresh air or calming scents like lavender. It also might help you to have a consistent smell for the room you sleep in, helping your brain to associate the space with sleep.

• Temperature matters. Many of us unknowingly sleep in rooms that are too warm. Interestingly, men and women often prefer different night time temperatures due to differences in core body temperature regulation and metabolic rates. The recommended temperature is ~17-18℃

• Foster suggested a refreshing take on this: don’t be afraid to sleep apart if it helps you sleep better. It’s not a sign of relationship trouble – it can actually strengthen it by ensuring both partners are well-rested.

4. Rethink Your Evenings

• Avoid stimulants like caffeine after 2pm.

• Alcohol may help you fall asleep, but it suppresses REM and fragments sleep in the second half of the night. Try swapping it for herbal tea.

• Create a wind-down routine. Foster noted that people often expect to fall asleep without preparing for it, like trying to land a plane without descending first.

• Swap stimulating evening habits for something calming: gentle yoga, reading fiction (not emails!), or even mindful breathing.

• Don’t use the hour before bed to catch up on emails or doom-scroll. Read, stretch, journal, or listen to something calming.

5. If You Wake in the Night...

• Don’t panic. It's normal to wake briefly — what matters is how you respond.
• Stay calm. If you’re awake for more than 20 minutes, get up and do something low-stimulus (no screens, no bright lights).
• Keep the lights dim and avoid the clock — clock-watching increases stress.
• Foster pointed out that sleep pressure builds naturally throughout the night, so even if you’ve lost a few hours, your brain will still benefit from whatever rest it can get in the second half.

In Summary

Sleep isn’t a luxury – it’s a biological necessity. Professor Foster's talk powerfully reframed sleep as something we must protect with the same diligence we apply to diet, exercise and mental health. It’s not always easy in the modern world, but the risks of ignoring sleep are too great.

So if you do one thing differently this week, make it this: go to bed 30 minutes earlier, get morning sunlight in your eyes, and start reclaiming your sleep as the superpower it is.

For further reading, I highly recommend Professor Foster's book Lifetime, which includes over 900 scientific references and practical guidance. Thank you again to Professor Foster for such an inspiring, data-rich session.