The Healthspan Map · Habits (Ch4)
Screens before bed, cut back
Compiled by Aamir Malik, PhD, Professor of Neuroengineering at Brno University of Technology, from published studies. He is a researcher, not a physician. Last updated 21 August 2026.
What this is linked to
| Condition or system | Direction | Strength | Evidence type | What was found | Source |
|---|---|---|---|---|---|
| Anxiety | Do this | Moderate | RCT / meta-analysis | Problematic smartphone use is associated with higher anxiety (OR 3.05) and perceived stress. | Sohn et al. 2019, BMC Psychiatry (opens in a new tab) |
| Brain fog & memory | Do this | Moderate | Systematic review | Screens (esp. before bed) disrupt sleep and fragment attention, worsening brain fog. | Sleep-cognition overview 2023 (opens in a new tab) |
| Chronic fatigue / low energy | Do this | Emerging | Established clinical | Evening screen light delays sleep onset, trimming sleep and worsening next-day fatigue. | Excessive daytime sleepiness review (AFP) (opens in a new tab) |
| Depression / low mood | Do this | Moderate | RCT / meta-analysis | Problematic smartphone use is associated with markedly higher depression (OR 3.17). | Sohn et al. 2019, BMC Psychiatry (opens in a new tab) |
| Headache & migraine | Do this | Moderate | Established clinical | Screen time/blue light before bed activates the brain and disrupts sleep, worsening migraine. | American Migraine Foundation (opens in a new tab) |
| High blood pressure | Do this | Emerging | Cohort / observational | Leisure screen time adds to sedentary behaviour and is linked to higher cardiovascular risk, especially in the less fit. | Screen time & CVD (UK Biobank) (opens in a new tab) |
| High cholesterol / dyslipidemia | Do this | Emerging | Cohort / observational | Leisure screen time and sedentary behaviour cluster with adverse lipids and metabolic risk. | Screen time & CVD (UK Biobank) (opens in a new tab) |
| Insomnia / poor sleep | Do this | Moderate | RCT / trial | Light is the dominant melatonin synchronizer; blue/bright evening light suppresses melatonin, dim light and a dark room preserve it. | Evening light-melatonin studies (opens in a new tab) |
| Obesity / weight gain | Do this | Moderate | RCT / trial | Genetic liability to TV and leisure screen time causally raises obesity risk (TV OR 1.55; leisure screen OR 1.62). | Sedentary behaviour & obesity MR (opens in a new tab) |
| Reproductive & sexual health | Do this | Emerging | Review / narrative | Late-night screens disrupt the sleep/circadian rhythm that governs testosterone, and laptops on the lap add scrotal heat that can impair sperm. | Sleep & men’s health (PMC7108988) (opens in a new tab) |
| Stress | Do this | Moderate | RCT / meta-analysis | Problematic smartphone use is associated with higher perceived stress (OR 1.86), anxiety and poorer sleep. | Sohn et al. 2019, BMC Psychiatry (opens in a new tab) |
| Vision problems | Do this | Moderate | Systematic review | Screen/near-work is tied to myopia progression (meta-analyses of hundreds of thousands of children) and to digital eye strain/dry eye as blink rate falls from ~18 to ~4 per minute. | Digital eye strain & myopia review (Myopia Profile) (opens in a new tab) |
| Neurological & Mental Health | Do this | Moderate | RCT / meta-analysis | Problematic smartphone use is linked to poorer mental health - higher stress, anxiety and depression. | Yang et al., Psychiatry Research 2020 (meta-analysis) (opens in a new tab) |
The Healthspan Map is part of Fix the Floor, a book by Aamir Malik. About the book