Neuroscientist Yousuf Aslam says the brain must feel safe to sleep

Sleep does not begin with a pillow or a well-drilled bedtime routine. It begins, according to Yousuf Aslam, with a brain that feels safe. Aslam, who studied neuroscience and biochemistry at Queen Mary University of London and now runs a commercial brain-training practice, told Newsweek that the one condition a brain needs before it can drift off is a sense of security, and that for millions of poor sleepers the problem runs deeper than a bad habit. Sleep clinicians describe the same territory in colder words, as hyperarousal and conditioned arousal, the ideas behind cognitive behavioural therapy for insomnia.

Sleep regulation runs on what Aslam calls a 'complex interplay' between neuroscience, psychology, neurochemicals and physiological processes. Two biological systems set the schedule: the circadian rhythm, the body's roughly 24-hour internal clock, and sleep-wake homeostasis, the pressure to sleep that builds the longer a person stays awake. Emotional factors, he said, can matter just as much as the biological machinery.

For sleep to arrive, the brain has to slow down and turn down the volume of its own thoughts. Aslam describes many people as feeling unsafe about what he calls future memories, anticipating negative outcomes, dreading tomorrow's responsibilities, or turning over a list of things left undone. A mind rehearsing threats is a mind still on duty, and the brain treats that vigilance as a reason to stay awake.

What a brain does when it feels unsafe

When the brain reads its situation as unsafe, it shifts into the sympathetic nervous response, the fight-or-flight state built for danger. Heart rate climbs, brain activity rises, and the body prepares to act rather than rest. That physiology is useful in an emergency and counterproductive at midnight, when nothing in the bedroom actually threatens the sleeper, yet the alarm keeps firing all the same.

People who cannot make that shift often reach for their phones. Aslam says he sees it constantly: poor sleepers spending hours on a device late into the night, trying to exhaust themselves into sleep rather than calm themselves into it. The screen becomes a way to wait out a nervous system that will not stand down, even as the light and the stimulation keep the alert rhythm running.

The pattern feeds itself. Kelly Murray, an adult sleep coach, says that after a long stretch of bad nights the brain starts to associate the bed, the bedroom, even the thought of sleep, with stress, which sets off the fight-or-flight response all over again. Clinicians have a name for it. Conditioned arousal is what stimulus control therapy, devised by Richard Bootzin in 1972, was built to break. The place meant for rest becomes a cue for alarm.

It needs to feel safe.

Underneath the feeling of safety is a measurable change in the brain's electrical activity. To fall asleep, the brain has to move out of the fast, alert rhythm of wakefulness and into a slower one before the deeper stages can follow. Neuroscientists track that shift by the frequency of the brain's waves, measured in cycles per second, or hertz, and grouped into bands from the slowest to the fastest.

Alpha out, theta in

Beta waves dominate when the mind is active and alert, useful for problem-solving and, in excess, a driver of stress, anxiety and restless sleep. Alpha waves are slower and calmer. Aslam calls them the gateway to cognitive relaxation. Sleep scoring puts it the other way round: alpha is the waking rhythm, and sleep onset is marked when alpha drops out and slower theta activity takes over for more than half of a 30-second epoch, which is stage one sleep.

Alpha sits in a relaxed but wakeful band, the kind of activity seen during light meditation or resting with the eyes closed. Excessive beta activity at sleep onset is the signature of the hyperarousal that clinicians see in insomnia. Beta amplitude also rises naturally as a person grows tired and enters the first stage of sleep, according to the Sleep Foundation, so a high reading is not on its own a sign that something has gone wrong.

The categories are not rigid switches so much as overlapping rhythms, and researchers still cannot reliably steer them. Writing in The Conversation in December 2023, Susan Hillier, professor of neuroscience and rehabilitation at the University of South Australia, cautioned that the mechanisms shaping brain states remain hard to disentangle, that no single imaging method captures the whole picture, and that the evidence behind apps promising to push the brain into a calmer frequency stays murky.

Why the safe brain sleeps better

Clinical work supports the idea that sleep cannot simply be forced. The Sleep Foundation describes alpha activity as a normal feature of the drift from quiet wakefulness into sleep, and notes that alpha waves also appear when a sleeper briefly wakes. It adds that most sleeping pills increase the amplitude and frequency of beta waves, a receptor-level signature of drugs acting on GABA-A.

None of that means a prescribed pill is failing to work. The beta increase is a receptor-level signature of drugs that act on GABA-A, and the same drugs shorten the time it takes to fall asleep and lengthen total sleep. Anyone taking a hypnotic should raise questions about it with the prescriber rather than acting on an EEG trace.

Alpha activity is a normal finding during the transition from quiet wakefulness to sleep. If it begins to overlie other brain wave patterns, this may be a sign of an abnormality or illness that may contribute to poor sleep quality.

The cost of a brain stuck in threat mode reaches well beyond a single restless night. Sustained stress reshapes the organ itself, not just the evening ahead.

The long shadow of feeling unsafe

Chronic stress has been associated with reduced volume in the hippocampus, the region central to memory and learning, though most of the causal work is in animals and a twin study by Gilbertson and colleagues suggests smaller hippocampal volume may in part precede the stress rather than follow it. The associated pattern is an overactive amygdala, the brain's alarm system, and an underactive prefrontal cortex, the seat of higher-order thinking and self-regulation.

Sleep loss then compounds the problem. In a 2007 study in Current Biology, Yoo, Gujar, Hu, Jolesz and Walker found that 26 people kept awake for about 35 hours showed roughly 60 percent greater amygdala activation to unpleasant images than rested controls, along with weaker connection between the amygdala and the prefrontal cortex. That was one night of total deprivation in a laboratory rather than habitual short sleep, but it describes a loop in which lost sleep feeds the fear response and the fear response steals more sleep.

How to help the brain feel safe

Aslam's central prescription is a nightly writing exercise aimed squarely at the stressors keeping the brain on alert. He recommends listing three things a person is grateful for from the day or from the past, three things they are grateful for about tomorrow, and four things they appreciate about themselves in the present. The idea is to move attention off the threat list and toward something settled, giving the brain evidence that the night ahead is not an emergency.

The gratitude evidence is real but thinner than it is usually made to sound. A 2009 study found that people higher in trait gratitude reported sleeping better, but it could not show that one caused the other. The intervention trial most often cited had 41 students, and found gratitude worked no better than constructive worry or simple distraction. A review of 19 randomised trials in 2020 found gains that were mostly in how well people said they had slept. The field's own summaries are more confident than its trials.

The mechanism lines up with the brain wave account. Gratitude pulls attention away from the threat-scanning, rumination-heavy activity associated with beta waves and steers it toward appreciation and calmer, future-oriented thought, which eases the transition into the alpha state that comes just before sleep.

Light, routine and the limits of rules

Timing still matters alongside the emotional work. Steady sleep and wake times help anchor the circadian clock, and dim evening light stops melatonin being suppressed. The much-repeated rule about daylight within 30 minutes of waking is on shakier ground: it comes from clinical light-therapy protocols for a specific disorder, where it means half an hour under a 10,000-lux box, and the sleep medicine academy rates the evidence behind it as low. Regularity is the better-supported half. An analysis of nearly 61,000 people found that how consistently they slept predicted mortality better than how long they slept, and irregular sleep has since been linked to cardiovascular disease.

A rigid routine can backfire, though. Murray argues that the standard bedtime rules, no screens, no food, no caffeine, no stimulation, can create more stress when applied too strictly, defeating their purpose. A pre-sleep routine works when it genuinely helps the nervous system move from on to off, not when it feels like one more test to fail.

The safety principle extends well past the bedroom. Social threats such as the fear of judgment, exclusion or failure trigger the same cortisol cascade as physical danger: a 2004 meta-analysis of 208 laboratory studies by Dickerson and Kemeny found that tasks combining social evaluation with a lack of control produced the largest cortisol responses and the slowest recovery. Oxytocin is often invoked here as a bonding hormone that builds trust, though the trust findings specifically have largely failed to replicate. The term psychological safety was coined by Edgar Schein and Warren Bennis in 1965 and popularised in organisational settings by Harvard Business School professor Amy Edmondson, whose 1999 study tied it to team learning.

Getting the transition right pays off during the day. Aslam said improving sleep can affect 'mental health as a whole, including improved focus, clarity, and memory abilities.' The American Academy of Sleep Medicine's position is that sleep is essential to health rather than optional downtime, and for anyone whose insomnia is persistent it names cognitive behavioural therapy as the first-line treatment. Nothing here is medical advice, and a long run of bad nights is worth raising with a clinician.

The through line across the research is that safety is not a soft idea layered on top of sleep science but a condition the brain measures and acts on. Before the body can rest, the brain has to conclude that the coast is clear. For a lot of people, the fastest route there is not a stricter routine but a quieter sense that nothing tonight requires standing guard, and the permission, finally, to let the alarm switch off.